Loading...
O-71-211 - 05/06/1971ORDINANCE NO 211 THE CITY COUNCIL OF THE CITY OF ROUND ROCK, TEXAS PASSED AND APPROVED SAID SOUTHERN STANDARD GAS CODE THIS 4z/ DAY OF )17,7e. , 1971. ATTEST: 6X2)16 /14 Sa/2 fi/gR6/7P.E- CITY SECRETARY 1767F/EzD e)/1./iee , PRO TEM SOUTHERN STANDARD GAS CODE ADOPTED MAY, 1953 BY SOUTHERN BUILDING CODE CONGRESS BOARD OF TRUSTEES 1969 EDITION WITH REVISIONS AND CHANGES OFFICIALLY APPROVED AT ANNUAL RESEARCH CONFERENCE Shreveport, Louisiana, Daytona Beach, Florida, Birmingham, Alabama, Augusta, Georgia, St. Petersburg, Florida, Biloxi, Mississippi, Chattanooga, Tennessee, Birmingham, Alabama, Shreveport, Louisiana, Clearwater, Florida, Dallas, Texas, Mobile, Alabama, Miami, Florida, Memphis, Tennessee, Norfolk, Virginia, New. Orleans, Louisiana, November 1-4, 1953 November 14-15, 1954 November 6-9, 1955 November 11-15, 1956 November, 10-13, 1957 November 9-12, 1958 November 1-4, 1959 October 31 -November 2, 1960 November 5-9, 1961 November 11-15, 1962 November 10-14, 1963 October 25-29, 1964 November 7-11, 1965 November 13-17, 1966 November 12-16, 1967 October 27-31, 1968 COPYRIGHT 1969 BY SOUTHERN BUILD:NG CODE CONGRESS 1116 BROWN -MARX BUILDING BIRMINGHAM, ALABAMA 35203 In no case shall oxygen ever be used. Low pressure (not in excess of 0.5 lbs. per square inch) gas piping shall withstand a pressure of at ]east 6 inches of mercury measured with a manometer or slope gage for a period of not less than 10 minutes without showing any drop in pressure. Higher pressure piping must stand a pressure of at least 10 PSIG, but never less than twice the maximum pres- sure to which the piping will be subjected in operationl, for a period of not less than 10 minutes without showing any drop in pressure. 211 TURNING ON GAS 211.1 Close All Gas Outlets Before turning gas into any piping, all openings from which gas can escape shall be closed. 21.1.2 Checking for Leakage Immediately after turning gas into a piping system, a thorough check shall be made to ascertain that no gas is escaping, 212 PURGING 212.1 Purge AlI Gas Lines After the piping system has been checked for leakage, it shall be purged. Under no circumstances shall a line be purged into the combustion chamber of an appliance. The open end of piping systems being purged shall not discharge into confined spaces or areas where there are sources of ignition unless precautions are taken to perform this Operation. in a safe manner by ventilation of the space, control of purging rate, and elimination of all hazardous conditions. 212.2 Light Pilots When an appliance is put in service, the appliance shall be purged and the pilots lighted. 213 OUTSIDE USE OF PIPE OR TUBING (a) Regardless of any installation or sizing requirements in this or any Other section, smaller pipe; seamless copper, or coated steel tubing of adequate size installed entirely outside a building may be used to connect gaslights and grills located outside a building. (b) When approved by the authority having jurisdiction and acceptable to the gas company, plastic tubing conforming to ASTM D2513 -66T and the following material specifications, may be used only underground for conveying natural gas to outdoor gas lights and grills. Material ASTM Standard Polyethylene, Type III, Grade 3, Class C(PE-3306) D1248 -65T 11-15 Polyethylene Type II, Grade 3, Class C(PE-2306) Poly(Vinyl Chloride) Type I, Grade 2 (PVC -1220) Poly(Vinyl Chloride) Type II, Grade 1 (PVC -2110) (c) This plastic tubing must be length, and may not be used within facturers' recommendations for the complied with. D1248 -65T D1784 -65T D1784 -65T buried in the ground for its entire or under any building. The manu- joining of plastic tubing•shall be 214 GAS PIPING IN MOBILE HOME TRAILER PARKS AND TRAVEL TRAILER PARKS Gas piping systems in mobile home trailer parks and travel trailer parks extending from the point of delivery to the terminal of the gas riser at each trailer site shall comply with the following specific provisions and with all other applicable provisions in Chapter I and Chapter II. (a) Protection of Piping Piping shall be buried to a sufficient depth or covered in a manner so as to protect the piping system from physical damage. (b) Prohibited Locations Piping shall not be installed underground beneath mobile homes or travel trailers with an enclosing foundation (c) Location, Protection and Sizing of Riser Where information is not available on the Location of the trailer supply connection, the gas riser to each trailer site should be placed in the rear one-third section of the site and not less than 18 inches from the roadside wall of the trailer. It shall be located and pro- tected or supported so as to minimize the likelihood of damage by moving vehicles. When the gas pressure at ,the terminal of the gas riser at each trailer site is 0.5 psig or less the minimum size of the gas piping outlet shall be 9i inch for other than undiluted liquefied petroleum gases. (d) Location of Shutoff Valves Outlets for the individual trailers and gas piping to any building supplied by the system shall be provided with a readily accessible manual shut off valve. (e) Connection of Trailer • Trailers shall be connected to the gas piping system with rigid pipe, listed connectors or semirigid tubing of adequate size and installed so as to be protected against physical damage. Provisions for flexibility shall be provided when necessary. II -16 Va i'v k v 2.. J 9‘ 9 — 7� GAS PIPING INSTALLATION 54-13 2.5.5 Connections: Connections to the gas piping system shall be made with pipe, listed connectors or semirigid tubing. Provisions for flexibility shall be provided when necessary. Connectors having aluminum exterior • surfaces shall not be used. 2.5.6 Demand Factors: (a) The hourly volume of gas required for any site gas outlet or any section of a park gas piping system may be computed from Table 9 of Appendix B. (b) Other gas equipment or appliances, other than site outlets, shall be computed at the manufacturer's maximum cubic foot per hour input rating or from Table 1 of Appendix B and shall be added to the figures given in Table 9 of Appendix B. 2.6 ACCEPTABLE PIPING MATERIALS 2.6.1 Piping Materials: (a) METALLIC Pip; .; PIPING JOINTS ANI) FITTINGS. " ct allic gas pipe shall be.stccl or xvrought-iron pipe complying with the USA Standard for Wrought -Steel and Wrought -Iron Pipe, 1;'36.10-1959.* Threaded copper, brass, or aluminum alloy pipe in iron pipe sizes may be used with gases not corrosive to such material. Aluminum alloy pipe shall be factory coated to protect against external corro- sion where it is in contact with masonry, plaster, or insulation or is subject to repeated wettings by such liquids as water (except rain water), detergents or sewage. Aluminum alloy pipe shall not be used in exterior locations or underground. Aluminum alloy pipe shall comply with the USA Standard Specification for Aluminum - Alloy Seamless Pipc and Seamless Extruded Tube, II38.7-1967 (ASTM B241-673) ** (except that the use of. alloy 5156 is prohibi- ted), and shall be suitably marked at each end of each length in- dicating compliance with the standard. lictailic pipe joints may be screwed, flanged or welded, and nonferrous metallic pipe may also be soldered or brazed with mate- rial having a melting point in excess of 1,000° F. *Available from the United States of America Standards institute, 10 East 40th St., New York, New Yolk 10016. **As,ailable'from the United States of America Standards institute, 10 East 40th St., New York, New York 10016, or the American Society for Testing and Materials, 191G Race St., Philadelphia, Pennsylvania 19103. Aka 1l,r?et / Filer. 4.44- x 1;•,.4,'1 A.1.Is4:..'.Jadvi 54-14 GAS APPLIANCES AND GAS PIPING • Metallic fittings (except stopcocks or valves) shall be steel, brass, or malleable or ductile iron when used with steel or wrought -iron pipe, and shall be copper or brass when used .with copper or brass pipe, and shall be aluminum alloy when used with aluminum aI- 1oy pipe. When approved by the authority having Jurisdiction, spe- cial fittings, such as saddle tees and gland type compression cou- plings, may be used to connect steel or wrought -iron pipe. Cast-iron fittings in sizes 6 inches and larger may be used fo connect steel and wrought -iron pipe \ellen approved by the authority having jurisdic- tion. (1.)) METALLIC TUBING ; TUBING JOINTS AND FITTINGS. When acceptable to the serving gas supplier, seamless copper, aluminum alloy or steel tubing may be used \yith gases not corrosive to such material. Copper tubing shall comply with standard Type Ii or L, of the USA Standard Specification for Seamless Copper Watertubc, H23.1-1967 (ASTM 1188-66a)** or the USA Standard Specifica- tion for Seamless Copper 'Tube for Refrigeration Field Service, 1123.5-1967 (ASTM B280 -66a).** Steel -tubing shall comply with the Specification for Electric -Resistance -Welded Coiled Steel Tub- ing for Gas and Fuel Oil Lincs, AS"1'\f A539-65,'*** or US.\ Stan- dard Specification for Copper Brazed Steel Tubing, 1136.35-1966 (ASTM A254-6-1)." Aluminum alloy tubing shall be of standard Type A or 11, or equivalent, complying with USA Standard Speci- fication for Aluminum -Alloy Drawn Seamless Tubes, I-138.3-1967 (ASTM B210-67),rt* or Type A or equivalent complying with USA Standard Specification for Aluminum -Almy Seamless Pipe and Seamless Extruded Tube, 1138.7-1967 (ASTM 112-11-67)." Alu- minum alloy tubing shall be factory coated to protect against ex- ternal corrosion where it is in contact \with masonry, plaster, or in- sulation or is subject to repeated wettings by such liquids as water (except rain water), detergents or sewage. Aluminum alloy tubing shall not be used in exterior locations or underground. ;Metallic tubing joints shall either be made with approved gas tubing fittings, or be soldered or brazed with a material having a melting point in excess of 1,000° F. Metallic ball sleeve compres- sion type tubing:fittings shall not be used, for this purpose. (c) PLASTIC PIPE, TUBING AND FITTINGS, 'When acceptable to the serving gas suppliers plastic pipe or tubing conforming \Vith specification ASTM 1)2513-68, Specification for Thermoplastic Ccs Pressure Pipe, Tubing, and Finings,':':-'` .or specification ASTM 1)25177-67, Specification for Reinforced Thermosetting Plastic Gas ***Avaiiah c from the American Society for Testing and Materials, 1916 Race St., Philatleli,hia, Pennsylvania 19103. **See See page 54.13. GAS PIPING INSTALLATION 54-15 Pressure Piping and Fitting,s,' X» and compatible fittings may be used for outside piping underground only. The installation shall be such as to avoid excessive stresses due to thermal contraction. PIastic pipe, tubing and fittings shall be joined by either the sol- vent cement ;nethod, adhesive method, heat -fusion method, or by means of compression couplings or flanges. The joining method used shall be compatible Nvith the materials being joined. The rec- ommendations of the manufacturer shall also be taken into con- sideration when determining which method is to be used. • The following shall be. observed when making such joints: 1. Plastic pipe or tubing shall not be threaded. 2. Solvent cement joints, adhesive joints, and heat -fusion joints shall be made in accordance with qualified procedures which have been established and proven by test to produce gas- tight joints at least as strong as the pipe.or tubing being joined. 3. Solvent cement or heat -fusion joints shall.not be made be- tween different kinds of plastics. 4. Heat -fusion or mechanical joints shall be used when joining polyethylene pipe, tubing or fittings. 5. Flanges, flared joints, or special- joints may be used provid- ing they are properly qualified and utilized. 6. When compression type mechanical joints • arc used, the gasket inaterial in the fitting shall be compatible with the plas- tic piping and with the gas distributed by the. system. An internal tubular rigid stiffener shall be used in conjunction svith the fitting and the stiffener shall be flush with end of the pipe or tubing and extend at least to the outside end of the com- pression fitting when installed. The stiffener shall be free of rough or sharp edges and shall not be a force fit in the plastic. A split tubular stiffener shall not be used. 7. The joint "shall be designed and installed to effectively sus- tain the longitudinal pull-out forces caused by contraction of the piping or by external loading. 2.6.2 Workmanship and Defects: Gas pipe or tubing and fittings shall be clear and free from cut- ting burrs and defects in structure•or threading and shall be thor- oughly brushed, and chip and scale blown. Defects in pipe or tubing or fittings shall not be repaired. When ***See page 54-13. LONESTAR,CAS COMPirf GENERAL DIVISION OF DISTRIBUTION RULES REGULATING THE INSTALLATION OF NATURAL GAS PIPIAG AND APPLIANCES In the absence of local ordinances governing' the installation of gas piping end appliances, all such work shall be done in accordance with the following rules and regulations in order that it may pass Company inspection. No work shall receive approval until all requirements, as set out herein, have been met. GAS PIPING REGULATIONS DEFINITIONS (1) C. The term "gas" as used herein shall mean natu- ral gas only. (2) house Pipinj. The terra "house piping" as used here- in shall mean the gas pipe end attendant fittings be- ginning et the fitti.ng or connection nearest the found- ation and outside of the outer well of the building structure, and Including all pipe, fitting°, and con- noetlona within end/or immediately adjacent to the foundaiton linen of the building or structure, whether concealed or visible. (3) Yard 1.fneTile term "yard line" as used herein shall mean the piping and attendant fittings beginning et the house piping end extending to the consumer pro- perty line or to the meter outlet, depending upon the location of the meter with respect to the property line. (4) Service Line, The term "service line" as used hero- in shell mean the piping and attendant fitting° extend- ing from the gas mein. to the meter or to the consumer property line, depending upon the location of the meter with respect to the property line. GENERAL (1) Meter Location. In piping any house for gas, the CAB Company shell decide end designate in every case the type of gas meter to be set and where the gas me- ter shall be located. The gas fitter shall first as- certain the meter location from the Gas Company and ex- tend the house piping to this point and install a pro- per meter loop for the setting of the gee meter. (2) Multiple Meter Insteiletfone. Where one or more meters ere desired for a given building, the Gas Com- pany may set r.e many meters as there are separate con- sumers•npplying for service, connecting the meters to'. one service pipe; provided that the house pipings lead- ing to such different consumers ere'extended to, and connected with,. their respective meter connection out- lets, are plainly end permanently marked to identify the part of the building served by each meter, and are run according to the requirementa of these regulations. (3) Delivery Pressure. Can will. be delivered to the consumer at 4 ounces per equate inch gauge pla:eure at the meter outlet. When the consumer hoe unynua1 gas consumption requirements end alien approval is requested in F;dve.nce of the installation of piping, the Gap Com - pony may, et its option, deliver Fen et either 5 or 10 pounds per square inch gauge pressure or et tt regulated distribution system pressure; the consumer nhall pro- vide additional pressure regulation es required. Cas shall not be delivered at one of the higher pressures only to compensate for inadequately sized yard or house piping. (4) Innururetion of Service, No person, firm or corp- oration, other than the Cas Company or its employees shall initially inaugurate gen service to o customer. Whore the Company ban discontinued gas oervico to a cus- tomer for any rcenon, no person, firm or corporation other than the Can Company or its employees sball re- inaugurate service to the customer. (5) Maintenance of Yard Line. It shall be the duty and obligation of the customer to maintain end repair the yard line regardless of whether the meter is installed at or near the building or at or near the property line. An authorized licensed plumber may, for the purpose of repairs, place the customer's yard line out of service except where the meter is located at or near the custo- mer's building, and there is no stopcock in Gr,e Company's service line at the point of connection with customer's yard line. In those cases, the Company shall be con- tacted to place the line out of service. (6) Existing Piping. Consumers gas piping installed prior to the effectiveness of thene regulations or piping in- stalled to supply other than natural gas may be convert- ed to natural gas if inspection and tests indicate that such piping will render satisfactory gas service and will in no way endanger life or property; otherwise, such piping shall be altered or replaced to conform with the requirements of these regulations. MATERIALS (1) Quality. All pipe used for the installation, ekten cion, alteration, or repair of any gas piping shall, either be new or shall previously have been used for' no purpose other than for conveying of gas. All such pipe shall be free from internal obstructions, foreign tr, tter, or imperfections which would render it unsatisfactory for the purpose intended. (2) Metallic Pipe, pi inn Joints and Fi.ttin's. Metallic gas pipe shall be black steel or wrought -iron pipe com- plying with ANSI Standard for Wrought -Steel end Wrought - Iron Pipe, B 36.10-1959 or threaded copper or brass pipe in iron pipe sizes. Metallic pipe joints may be screwed, flanged, or welded, and nonferrous metallic pipe may &leo be soldered or brazed with material having a melting point in excess of 1,000 degrees F. Metallic fittings (except, stopcocks or valvas) shall be steel or malleable or ductile iron when used with steel .or wrought -iron pipe, and shall be copper or brass when used with copper or brass pipe, Cast-iron fittings in sizes over 3 -inch may be used for steel end wrought -iron pipe. (3) Metallic Tubing Tubing ,Tointe end Fittinen. Sermlees copper or steel tubing may be used for geri pin Cop- per tubing shall comply with standard Type P or L, of the ANSI Standard Specification for Seemlesn Coppet.Wstertuhe, 1123.1-1967 (ASTM B280 -66e), Steel tubing shall comply with the Specification for Electric-penistcnce-Welded Coiled Steel Tubing for Gas and Fuel 011 Lincs, ASTM A539-65 or ANSI Standard Specification for Copper Lraa•ed Steel Tubing, 836.35-1966 (AST1f A254-64). Metallic tubing joints shall either he made with approved gas tubing fittings, or be soldered or brazed with a ma- teriel having a melting point in excess of 1,000 degrees F. Metallic ball sleeve compression type tubing fittings shall not be used, • (4) Plastic Pipe, Tubing end Fittings. Polyethylene plastic pipe or tubing conforming with Specification for Thermoplastic Can Presnure Pipe, Tubing, r.nd Pit- tinyn, ASTM D2513-68 and compatible fittings may he • used for outntde piping; underground only. `ti,e i;u;ta?'Atop rhall be such as to myoid excessive - 47trc77.ucs c,lu 10 t'.•iermel contraction. oly-tthylene plrstle pipe, tubing, and fittings shall !)c joined by either the hest fusion method; coxpreaoion rr)u!)}.;.nee, or flanges. Heat fun ion joints shall be sande in accordance with procedures recommended by the rianufecturer. Compression couplings ahell be "those re- commended by the manufacturer for use on polyethylene plastic pipe or tubing. An internal tubular rigid stiffener shell be used in conjunction with compression • couplings end the stiffener shall be flush with the end of the pipe or tubing and extend et least to the outside end of the compression coupling vhen installed. The stiffener shall be free of rough or sharp edges and shall not be e force fit in, the plastic. A split tubular stif- fener shell not be used, Joints shell be designed and installed to effectively sustain the longitudinal pull-out forces caused by con- trec.tion of the piping, r MINIMUM PIPE SIZES, (1) House piping aha11 be sized to provide gas at peak demand erLth a pressure drop of not more than 3/10 -inch- • es of eater column in the overall system. (2) The minimum size and nnximuzm lengths of pipe for louse piping may be determined from Table I. In no ceee shall any section of piping be smaller in nine than Any pipe which it supplies. Yard lines shell be included with the house piping in determining the mini- mum nine end mexi.mem le_ngtho of pipe permissible for the .system except twat when service is to be aupplied•from en inters.cdiete pressure main end the meter and service regulator ere to be installed et the building, the yard line need not be included. (3) Drench lines (pipe extending to any single riser pipe) and riser pipes (vertical piping to the gas out - )et) shell be not lens then 1/2 -inch in eine and in no case smaller then the connection on the appliance to be eerved. (4) Yard lines, when eervice Is supplied from an inter- mediate pressure (pounds per square inch) main and the meter end regulator are to be installed at the building, shell be 3/4 -inch in cite„ except that when the building to he served has gas requirements exceeding 700 cubic feet per hour or the length of the yard line exceeds 200 feet, the Gan Company shall be consulted for correct yard line size. (5) For conditions other thtn those covered by these provisions such ne longer runs or larger dined of pip- ing or greeter nose demo.nda, the Gas Company shall be consulted for correct piping sicee. TABLE I PiINIMUM PIPE SIZE FOR HOUSE PIPING 2 7 2 4 u;.M..ee cif Pipe 1.. lune. 1.4.,' lee, iS - )£ 1 i54 7'/e 2 3 4 0 0 Deanne in cubic lr et per hnu * 15 7411721345 750 5220 2460 f 53.0 23,§10 38700 79000 30 55 /120 241 535 850 5780 4700 9700 27370 57350 45 44 99 199 495 700 1475 3900 7900 23350 45600 60 35 84 173 3380 610 5290 3450 6000 /59330 111139500 75 S 77 155 345 145 1123 9000 6000 17310 133300 5'0 ! 70 541 310 490 1000 2700 5500 15000 i32250 55 163 131 205 450 9202•:50 5100 14623 129450 50 70 170 770 420 060 17390 4800 136+10 27920 50 109 742 389 760 2000 4350 12240 23030 10 100 275 350 720 1950 4000 51160 22800 10 205 320 660 5780 3700 10930 21100 ,0 I92 190 300 620 1640 3490 9000 19749 0 170 285 500 7580 3750 9000 10610 0 1570 270 545 1490 3000 51300 57660 I0 140 274 450 1230 2500 7000 14420 0 112137 )29 09n 60 i2115� * Demand shell he determined in cubic feet per hour by dividing the !)til Btu input of all nn',1n:70r9 (nn i.ndic.At 'd by the n)•onliftr.trl?-ernl .(6) A piping plan showing the proposed location and sires of pipe shall be submitted to the Gas Company for approval erior to the installation of a gaa piping system to serve multiple buildings or mobile homes. z* (7) Additions to existing house piping and increases in`` demand shall conform to the provisions of these regula- tions. Additions shall not be made to existing pipe which is smaller than that permitted by these provisions; such existing piping shall be replaced by the proper size pipe. . INSTALLATION (1) Gas piping in buildings shall be supported with pipe hooks, metal pipe straps, or hangers suitable for the size of piping and of adequate strength and located at proper intervals so that the piping cannot seg or be moved accidentally from the installed position. Gas piping shall not be supported by other piping. (2) The building shall not be weakened by the instal- lation of any gas piping. (3) Cas piping within a building shall be electrically continuous and bonded to a grounded electrode. (4) House piping within the foundation lines of e build- ing shall not be buried or in contact with the ground or fill under the building and shall not be installed in concrete. (5) Gas pipe shall not be run closer than 6 inches to any electric wire unless such wire be inside of conduit. (6) Pipes shall not be bent; approved fittings shell he used for making changes in direction. (7) Pipe threads which are stripped, chipped, corroded, • or otherwise damaged, shall not be used. (8) Defective pipe or fittings shall not be repaired but shall be replaced. (9) White lead or other suitable material shall be used for threaded joints, and is to be applied speringly on- ly to the male threads. No shellac or cement may be used, and caulking is strictly prohibited. (10) Three way valves, bushings, street ells, left bend or left and right hand threaded pipe nipples, couplings with -a slip joint or packing, and pipe peddler, shall l • not be used in house piping. Pipe noddles t,nd gleed type compression couplings may be installed on outside piping underground only. (11) Branch outlet pipes shall be taken from the top or aides of supply lines, and never from below. • (12) Yard lines shall in no instance be installed in the same ditch with sewer piping. (13) Metallic piping in contact with the earth or other material which may corrode the piping, shall have an ep- proved coating, be insulated from other underground structures, and be placed under cathodic protection us- ing galvanic anodes. (14) Yard lines shall be installed with a minimums cover of 18 inches. (15) Where the gas meter is to be located at the pro- ' party line, a riser must be used in the yard line rhesd of the house piping. A manual shut off valve sl,e;ll be installed in the riser not less than 4 inches above ground. (16) Meter loops shall be constructed in accordance with _-drawings which follow. (17) Plastic pipe shall be installed underground on un- disturbed or well compacted coil. An electrically con- ductive wire shall be installed adjacent to the pipe to facilitate locating it with an electronic pipe locator. (18) Plastic pipe shall not be extended shove ground nor into or under any building or other structure. (19) Service risers must be constructed of steel pipe end they must be protected from vehicular traffic. Risers con • - nected to plastic pipe must be supported by a pont driven or set into firm ground, or otherwise stabilized to pre- vent transferal of force due -to natural settling or ecci- ' dental movement of the riser to the polyethylene pipe. - 2 - INSPECTION AND TESTING '7(1) ee•nn any gas piping has been installed, but• bo- fore•any part of it is concealed, it shall be inspected by the Cos Company to ascertain that the pipe has been installed in accordance with the provisions of these regulations and that materials used are of the size and quality prescribed. The piping shall then be subjected to en air pressure teat under which not lees than a 12 - inch mercury column shall be maintained for 15 minutes without any drop. Plastic piping uhall be Subjected to an air pressure teat of not less than 50 psig for 15 min- utes without any drop. Yard lines which are to convey unmeasured gas shall be subjected to an air pressure test of not less than 75 psig for 15 minutes without any drop. (2) If all the piping cannot be installed before conceal- ing part of it, inspections shall be called for as the GENERAL work progressea. At each auch inspection, the air, pres- sure test shall be applied. (3) When all gas cocks are in place and appliances in- stalled, a final inspection shall be made. (4) Plumbers should always inspect their work and be certain that it has been installed according to specifi- cations and is free of leaks before calling for an in- spection. When reinspection in required becauee of un- satisfactory work or material, a charge of $4.00 will be made for each additional inspection after the second visit by Company inspectors. (5) Any additional piping or outlets installed later must be reported for inspection and test. (6) Water shall not be used in testing gas piping for leaks. Piping in which water has been introduced will be condemned as faulty. APPLIANCE REGULATIONS (1) pproved Appliances.All domestic ranges, water heaters, floor furnaces, unit heaters, central heating appliances and other similar domestic gas • applicncee should bear the seal of`epproval of the American Gas Association for use with natural gas. (2) Clearances. All gas appliances, domestic or com- mercial, and venting material must be inotalled with minimum clearances from combustible materials as spe- cified by the American Gas Asaociatfon. Gas appli- ances shall be located a safe distance from combusti- ble furnishings, such as curtains, drapes, etc. so that continued or intermittent operation will not create a hazard to persons or property. (3) Gas Cocks. All gas consuming appliances shall be provided with a lever handled, tee handled, or flat head gen cock located in the riser between the floor and the union at the appliance. It is recommended that a safety gas cock be used wherever possible. (4) Apejlence Connectors. Gas connections to all ap- pliances shall be made by using rigid iron pipe size connections, semi-rigid approved aluminum tubing connectors or AGA approved flexible braes tubing connectors. (5) Appliance Adjustment and Operation. Every appliance_ shall be properly adjusted after being installed end'the consumer shall be instructed as to its safe operation. (6) Applinnce Location. All gas appliances shall be so located that they are readily accessible for operation and servicing. (7) Venting Appliance Regulators. Appliance regu lators which ere not equipped with an approved leak limiting device shall be- vented to a con- stant burning pilot or to the outside atmoaphere. (C) Pee of Air or 0):', cn Under Prenrure. 1, 'here air or oxygen under pressure is used in connection with the gas supply, effective means shall be pro- vided to prevent air or oxygen from passing back into the gas piping. No blower or compressor shall be installed with the suction side connected to the gas supply without providing suitable means for preventing the lowering of the gas supply pres- sure below a normal operating level. (9) Flammable Vanors. Gas appliances shall not be inotelled in any location Where flanxnr,ble vapors ere likely to be present, unless the design, 'oration and installation are ouch es to elimi- te the possible ignition of the flammable va- ers. (10) l"nnufncturer'a Tnatnl1ation Instructions. A11 appliances must be installed in accordance (11) Electrical -Connections. All electrical con- nection between gas appliances and the building wiring shall conform to the latest epproved edi- tion of the National Electrical, Code. VENTILATION OF APPLIANCES (1) Appliance Location. Appliances shall be installed in a location in which the £ac+lities for ventilation permit satisfactory cosrbuetion of gae, proper venting, and the maintenance of ambient temperature.at safe limits under normal conditions of use. (2) Combustion Air. Appliances installed in closets or confined spaces shall be provided with adequate combustion and ventilating air. When the closet or confined space has a ventilated attic a- bove and a ventilated crawl space below, combus- tion and ventilation air may be provided by an opening in the ceiling and another opening in the floor. Each opening to have a free air area of 1 squ. in. for each 1,000 Btu input of the appli- ance. ,In closets or confined space with concrete slab floor construction but with a ventilated attic above the ceiling, air for combustion And ventilation may be provided by eliminating the ceiling above the closet or confined space. Appliances installed in locations where com- bustion and ventilation air cannot be provided as listed above, then means must be provided, such as the use of metal duct pipes for bring - in sufficient air from the outdoors. The mini- mum dimension of rectangular ducts shall be not less than 3 inches. (3) Forced -Air Central Venting Plants. Return - air connections in the furnace room, or direct- ly above or below the furnace room, shall he co made as to preclude any possibility of air being drawn from the furnace room into the return air duct by action of the furnace fan. (4) fascial Condition. Operation of exhaust fans, kitchen ventilation systems or fireplaces may create conditions requiring special atten- tion to avoid unsatisfactory appliance operation. VENTING OF APPLIANCES (7) Vents to Cas Fired pplinncee. All appliances constructed and approved en vented equipment, in- cluding hut not confined to all water heaters, floor furnaces, vented circulators, vented gas steam radiators, vented well heaters and furnaces, unit heaters, all tvnce of o ; e met, anti all gas fired air conditioners, shell. be Properly vented in accordance with approved Ameri- can Cap Association Standards. Any heating appliance installed in any public school classroom, assembly hall, hotel, tourist court, or any similar establishment, shall be properly vented. (2) pes of Vents and Approved Materials. Type A flue or vent is a flue or vent of masonry or reinforced concrete, or a Imetal smokestack. .Type II gas flue or vent is vent piping of non- combustible, corrosion resistant materiel cf sufficient thickness, croon sectional area, and heat insulating quality, to avoid excess tempera- ture on rd_jncent combustible material and certi- fied by a national recognized testing Agency, such as Underwriters Laboratory. Type B-W gas flue or vent is a Type B vent list- ed•to insure a nafe and satisfactory installation in four-inch wood wall construction. Type C gas flue or vent is flue or vent piping of sheet copper of not less than the equivalent of No. 24 U.S.Stendard gauge', or of galvanized iron of not less than No. 20 U.S. Standard gauge, or of other approved corrosion resistant material. . (3) 'lope A flues or Vents. Type A flues or vents shall be employed for venting all incinerators, all appliances which may be converted to the use of solid or liquid fuels, and all boilers and warm air furnaces, except where such appliances ere ap- proved for the use of Type B gas flues or vents. (4) ape B C.ns Flues or Vents. Type B gas flues or vents shell be used only with appliances approved by American Cas Aesnciation which produce flue gen temperatures not in excess of 5500 Fahrenheit at the outlet of the draft hood when burning gas et the manufacturer's normal input rating and not specifically required to be vented to Type A flues or vents. Type B vent material is not suitable for use with coil type eater heaters. (5) Type C Cas Flues or Vents.Type C. flues or vents shell be used only for runs directly from the space in which the appliance is located through the roof or exterior wall to the outer air. Such flues or vents shall not be installed in any attic or con- cealed space, nor through any floor. Installation with reference to clearance to combustible con- struction and passage through wall or roof shall comply with American Cao Association Specifica- tions. (See Table II) (6) Vent Sizes. The size of the vent from any ap- pliance shall not be smaller at any point than the vent collar of the appliance to which the vent is connected. Where more than one gas appliance is connected to a common flue or vent, the area of the vent after the junction shall be not less than the area of the largest vent, plus fifty per cent (50x) of the combined area of the other vent or vests. In connecting to Type A vent, the connections should be made at different levels, (7) Urr:ft Hoods. Every vented appliance, except incinerators, dual oven type combination ranges, end units designed for power burnere or for forced venting, shall have a draft hood. (8) Thimbles. Flue or vent connectors, other than Type 15, shall not peso through any combustible walls or pertitione unless they ere guarded at the point of passage by ventilated thimbles. A protective flange or vent pipe collar may be meed if placed ea each surface where epproved Type B vent passes through wall, ceiling or floor provided, recommended clearances to combustible material are mcintained. (See Table I1) (9) Combination Venting. Cos eppliancea must not be vented into a flue, or stack to which 'welt- /`/ ances burning other fuels are connected, unless such gas appliances are equipped with safety pilots. No gas appliance vented by natural draft shall be connected into a vent. flue, chimney, or flue or vent connector on the discharge side of a mechanical flue exhaust. (10) Vertical Stack, The vertical stack to the outside'shall extend through the roof jack and to a height of not less than two feet (2') above the highest part of the roof or other obstruction with- in a horizontal distance of fifteen feet (15'). (11) Horizontal Runs. No horizontal run of vent shall be more than seventy-five percent (757,) of the height of the vertical stack. Horizontal vent runs shall have n continuous rise of at least one-half inch (1/2") per foot. (One inch (1") rise per foot is desirable.) (12) Concealed Vents. Concealed vents, and vents exposed to low temperatures, shall always be Type A or Type B materiel. This includes, but is not confined to, stacks through, and cross -overs in, an attic. (13) Vent Fittings. Use of 90 elbows is not per- missible in attic cross -overs end.should be a- voided, if at all possible, in all other cases. (Use 450 elbows.) Use of common tees is not acceptable; Y's, air -flow tees or lateral s£amese should be used for junctions. TABLE II 1IIAITUK DISTANCE FROM COMBUSTIBLE CONSTRUCTION (Except as otherwise specified in the listing of a nationally recognized testing agency) • Appliance Boiler Vary Air Furnace Water Heater Ream neater Floor Furnace Incinerator Draft Vood 6 fneies 6 inches . 6 inches 2 inches 9 inches Not Permitted Metal Flue or Vent Connectors Crype C) 6 inches 6 inches 6 inches 6 inches 9 Inches 18 inches Flue or Vent Connectors (Type B) 1 inch 1 inch 1 Inch 1 inch 3 inches* Not Permitted * 3 inches for a distance of not less then three feet from outlet of the draft hood. Beyond three feet the minimum clearance is one inch. . COMPLIANCE (1) These rules and regulations are intended to protect the public by assuring the safe and satis- factory utilization of gas. The firm or person making the installation shall be responsible for complying with the foregoing appliance installation rules. The customer shall be responsible for main- taining his gas appliances in a safe operating con- dition.' (2) If, upon inaugurating gas service to e premises, the serviceman observes a gas appliance which is not installed in accordance with Company's rules, service to the premises may be inaugurated only if; (a) the unsatisfactory condition is called to the attention of an adult member of the household end the member is advised that the appliance should not be used until a proper condition for use hes been effected (b) the appliance is left out of service, (c) notation is made on the uork order that the appliance was left out of service, and (d) the signature of an adult member of the 1.=t'se- hold is obcained on the work order. 4 SET Ii LINE HIGH PRESSURE LOW PRESSURE C C FRONT VIEW HIGH PRESSURE c- A. t() 4,,..4',%‘:-?�Ti ra-4ia,.f„€-)V4-- 1.. - \ a 1y FRONT VIED/ HOUSE TYPE METERS SET AT BUILDING L &7.iii-i1,A4' /l •,P t.4 FRONT VIEW TYPE No. 00, 0 Emco 150, 175, 250 Rockwell 513, 175 American IA. 175 Sprague 175 Sprague Combination No. 1 Emco, 415 Rockwell 425 American No. 2 Emco 1013 Hectic 2013 Metric No. 2 Sprague No. 3 Sprague 1 1 1 1 1• 154 154 1 154 14 151 6 6 6 7 814 6-7/8 L'4 7-3/16 634 2513 Metric 134 4 3013 [,ferric 155 11 14 31 15 934 134 134 155 x 114 14 2 z 15: 359 Metric 144 11 17 31 I5 11 14 2 134 x 14 2 x 154 2 x 154 750 Roc well251 11 17 31 15 11 14 2 155 x 24 2 x 144 2 x 144 17 31 15 11 14 2 1'4x154 2 x134 2 x131 LOW PRESSURE C •14. r 3 • . ry 4 N) FRONT VIEW Dimensions shown below are in inches •rT, C : d ylti�1� iV SIDE VIEW o fill ey '.tom SIDE VIEW C 1144 114 114 1155 114 1255 1254 14 13 14 13 1234 D 23 23 23 23 23 24 24 27 27 27 27 27 E 10 10 10 10 10 10 10 15 15 15 15 15 F 754 74 74 74 74 74 74 94 94 931 94 934 1 1 1 1 1 1 1 1 1 H 14 15( 14 154 15( 14 154 14 14 14 14 1 1 1 1 1 144 x 1 155x1 K 134x14 14 1i;z134 154x1 14 x 14 134 144x14 Lq• 14x1 2 r 154 155x1•'4 2 x134 134 z I 2 r I5; 14x 134 2 x14 No. 5 Sprague 2 _10-7/8 I7 32 15 11 14 2 2 x 1 2 1000 American 2 11' 17 31 15 4f 24 x 2 �� 11 1% 2' x}21% 2 2'/,X2 Dotted lures denote material furnished by consumer G. inlet piping, stopcork, and regulator sixes. 1%" size regulators are special high volume L•• insulating bushing 154 154 14 155 154 2 x 154 154 2 x 134 14 2 x 14 135 2 x155 2 z 135 2 2 2 :4x2 2V X 2 with .5 " orifice. 14 13; 1x4 14 154 134 2 2 2 2 2 - 5 - FRONT VIEW SIDE VIEW MANIFOLDED HOUSE TYPE METERS SET AT BUILDING UNE • • FRONT VIEW SIDE VIEW If manifold installation is served from I.P. lines, distance from ground to top of stopcock is 2G" and Company furnishes nil fittings between regulator and meters. Dimensions shown below are in in I) TYPE A B C D E F G4 H J It I.. , M :,. No. 00, 0 Erre,, 1 6 28 23 10 7A 1 15i x 1 1'''/ z I''4 x 1 14 x 1 J51 154 1', c 150. 175, 250 Rockwell 1 6 28 23 10 754 1 15i x 1 15/4 x 1,1 x.1 IX. s 1 154 r 1 1% 1;4 511, 175 hmericen 1 6 28 23 10 7'4 1 114 z 1 15i x 154 x 1 154 s 1 { lib x 1 g I;: 1% I/., 175 Sprague 1 6 28 23 10 754 1 154 z 1 PA x 154 x 1 1% s 1 1'/< x 1 i 15; 114 175 Sprague Combination 1 6 28 23 10 755 1 1 1 1 i 154 x 1 114 I e IiO. 1 Emco, 415 Rockwell 114 7 31 24 10 754 P4 155 x 1''% 115 154 2 x 15; 2 x 15 i 5`>i 425 American 1% 81/4 31 24 10 754 lY 154 z 1!( 115: 154 z i14 154 x 155 155 x 154 1 114 1;5 iio. 2 Emco 154 8 34 27 15 94 ll 2 • x 154 2 x 2 x 155 2 x 1'''A 2 z 115 2 is 1;5 11,5 100 Metric 201) Metric 1 6-7/8 1 r 34 u.b 34 ' 34 27 27 15 15 954 r 9/e 154 i/ 156 2 z 1/ ' 154 s 154 z 1 2 x 2 x 54 l 114 x 1 2 z WI i`74 a 1 2 x iio j 154 2 x 151 1'., 2511 14c;ric 155 8% 34 27 25 9:4 1!,1, 2 . 154 2 x 2 x 155 2 It: 11 2 z 154 i 2 x 151 . 15; No. 2 : psague154 7-3/16 34 27 15 954 154 155 x Iii 155 x 155 x 1'/; 155 x 154 1`55 x l54 i4 7' 4 No. 3 S,.r;gue 155 614 34 27 15 936 154 2 x 1% 2 x 2 x 154 .. a 155 2 z 151 1 2 .. 1% , ;;5 G6 Inlet prprng, stopcock, and regulator sizes. 1re" size regulators arc special bib volume with i;:z°' orifice. L°6lasulating bushing LOVI PRESSURE CURu M E ER EC<ST/.LLATION Dimensions shown below are in inches TYPE A St c f n i r. . 1 0.1 50 Hectic Crab 100 %nettle Ca&cb No. 0 ENG, C446 tto. 1 [.aco Cntb 13 13;4 13 14 7 6 7 5 70 20 20 jj 2t I 154 1 154 {{ 114 { 1+.1-i!!! 1`z 1`,.4 354 7 154 15e 154+ ? 1' 154 r 1 ) i.'ti : 1 i x 1 1 li Dolled lines denote material fr'r:ris::al by co: .:-r:r G° Insctlai nrr Nviou i ushirtr 6 MINIMUM REQUIREMENTS FOR CUSTOMER INSTALLED PLASTIC PIPE Material Material for plastic gas piping shall be polyethylene 2306 or 3306 manufactured in accordance with ASTM D-2513 Specification for Thermoplastic Gas Pressure Pipe, Tubing, and Fittings. Installation Polyethylene pipe shall be installed underground on undisturbed or well compacted soil with.a minimum cover of 24 inches. An electrically conductive wire must be installed with the piping to facilitate locating it with an electronic pipe locator. Polyethylene pipe must not be extended above ground and it must not be extended into or under a building, vault, or other enclosed structure. A minimum of 12 inches clearance must be maintained between the buried gas piping'and other underground structures. Additional clearance must be provided in the vicinity of steam, hot water, power lines, or other sources of heat. Joint Requirements Heat fusion or mechanical joints must be used when joining polyethylene pipe or fittings. /3 Heat fused joints must be made with a heating device that heats the mating surfaces of the joint uniformly and simultaneously to esseptially the same temperature. Such joints must be made in accordance with the recommendations of the pipe and fitting manufacturer. Mechanical joints must be made with compression couplings recommended for use on polyethylene pipe by their manufacturer. An internal tubular rigid stiffener must be used in conjunction with the coupling. Service Risers Service risers must be constructed o£asteel.pipe and they must be located so as to be protected from vehicular traffic. The risers must be supported by a post driven or set into firm ground, or otherwise stabilized to prevent transferal of force due to natural settling or accidental move- ment of the riser t� the polyethylene pipe. Inspection Piping must be inspected during installation and just prior to backfilling for cuts, scratches, gouges, or other imperfections. Pipe containing any harmful imperfection must be removed from the system. Tes ting Polyethylene piping must be tested with air, prior to being placed in service. Each joint should be tested for leaks by application of a soap solution. In addition, the completed system must be subjected to a stand-up air pressure test at not less than 75 psig for at least 24 hours to demonstrate that it does not leak. Lone Star Gas Company should be ,notified in advance of the test so that &representative nay witness the results. Repair of Damage Polyethylene pipe which has been damaged must be repaired by removal of the damaged section as a cylinder and replacement with a new section of pipe. It is not permissible to patch or clamp a leak on polyethylene pipe. r? • N.. rcE • POLYETHYLENE PIPE FOR NATURAL GAS Since 1950 the growth of industrial plastics has been truly phenomenal. Plastic piping was first introduced in water, sewage and chemical waste handling applications in the 1950's and enjoyed growing adaptation to the gas distribution field in the 19601s. Users of plastic piping have learned that taking advantage of the unique properties of plastics results in safe, serviceable, rugged and economic systems. The gas utility industry use of plastics continues to gain an ever increasing; share of new distribution installations as indicated by Figure 2. In a brief span of a decade, plastics pipe use has grown from 0. 3% of total miles of distribution pipe installed annually to 23. 4% in 1969. The future appears to be even more rosy. Companies not now using plastics pipe for various reasons are expected to find more and more incentives as improved resins and more than one full system of pipe and fittings are available for purchase. There appears to be strong similarity in the attitudes of companies who have not been using plastics pipe. Among this small group there is an indication, reported by CHILTON'S GAS magazine, that the nonusers would continue to evaluate plastics. Among a larger group of companies currently using plastics pipe, forty- eight percent expect an increased rate of installation during 1970..Some thirty-five percent in the user class expect to continue installing plastics of f41 1t�25iAtlAf � �-1--.1A10,41,r� nASff�Ct t !E}i Of - , .............. • ... ...OWN! ......r • A]�'o 39 1144 HL1 1Sb2 1932 195 1964 19'33 • 193.6 K;;l • K•43 1969 • Fig. 2. Plastics pipe's share of total new distribution pipe market. 67. at the same rate as in 1969..Plastics usage is continuing on an uptrend at a growth rate of 30% annually. Some utilities through out the country, concerned with total per- formance in gas distribution, have been waiting for a "full system" approach that makes use of the toughest of the known polyethylenes and a line of required fittings of the same resin and of equal quality as the pipe itself. Among types of plastics pipe material available for gas distribution, polyethylene stands at the top.with over seventy-nine percent of the total, following by.polyvinyl chloride at fourteen percent, while acrylonitrile butadiene styrene and cellulose acetate butyrate make up the last seven percent. Polyethylene is the most popular of the plastics material used. Its acceptance is growing and 98. 6% of those who have used it are satisfied with its performance. Indications are that the use of polyethylene material is more than keeping pace with the expanding usage of plastics pipe. Plastics pipe usage throughout the United States is shown in Table I by states. Colorado tops the list with over 3l million feet installed as of December, 1969, followed by Texas and Nebraska. Largest forecasted user for 1970 is Nebraska with over 6. 5 million feet. Operating pressures for systems in which plastics pipe is used are: Under 1 PSIG 10%. 2 to 25 PSIG 14% 26 to 60 PSIG 72% . 61 to 100 PSIG 4% 10 i TABLEI TOTAL FOOTAGE OF PLASTICS PIPE OPERATING IN UNITED STATES AND CANADA Alabama Alaska Arizona California Colorado Connecticut District of Columbia Florida Georgia Hawaii Illinois ndiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada flew Hampshire PN'ew Jersey Ne .w Mexico New York North Carolina North Dakota Ohio ©klahorna Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas 1ltah Virginia Washing ton West Virginia Wisconsin Wyoming TOTAL - U.S. As of December 1969 1970 Anticipated Use 124,040 53,000 . 1,500 1,500 11,667,000 1,908,000 4,167,102 2,249,000 31,380,438. 1,960,800 33,200 71,000 4,200,000 2,475,000 1,123;800 683,000 2,870,000 - 856,000 200 5,000 10,540,879 1,425,100 1,640,000 670,000 1,237,622 597,000 342,764 75,000 1,655,700 492,000 1,132,037 645,500 60,000 10,000 157,750 39,000 56,154 99,500 ' 8,032,800 4,429,800 10,257,200 2,861,000 8,000 - • 10,000 3,245,337 1,248,300 10,000 18,660,918 •. • 6,671,400. 11,512,400 910,000 918 800 . 2,518,100 1,640, 500 70,500 22,000 2,243,650 1,741,000 1,858,872 771,133 150,000 170,000 • 2,771,141 3,700,000 251,000 . 181,000 173,800 ' 35,000 5,122,074 2,672,660 1,231 • 1,200 -4,200,000 865,000 161,000 55,000 1,684,748 533,000 19,220,793 5,185,700 65,416 6,500 221,186 . 282,000 133,580 • 23,000 572,456 477,776 . 8,668,875 2,874,000 363,078 • . 50,000 Canada TOTAL Grand Total 177,040 3,000 13,575,000 6,416,102 33,341,238 104,200 6,675,000. 1,806,800 3,726,000 5,200 11,965,079 2,310,000 1,834,622 417,764 2,147,700 1,777,537 70,000 196,750 155,654 12,462,600 13,118,200 18,000 4,493,637 10,000 25,332,313 12,422,400 1,718 4,158,600 92,500 3,984,650 2,630,005 320,000 6,471,141 432,000 208,800 7,794,734 . • 2,431 2,065,000 216,000 . 2,217,743 24,406,493 71,916 503,186 156,530 1,050,232 11,542,875 413,078 171,559,259 51,743,169 223,302,428 14,350,658 9,880,000 24,230,658 185,909,917 61,623,169 247,533,085 29 The most frequently used operating pressure is under 60 psig. *During 1970 plastics pipe uses are projected to include: New Services New Mains Insertions in Existing Services Insertions for Existing Mains Tubing for Gaslights and Grills *CHILT ON' S GAS magazine • 12, 700, 000 Feet 16, 600, 000 Feet 7,000,000 Feet 700,000 Feet -3, 700, 000 Feet The economy of plastics over steel pipe is dramatic and will put gas within reach of more residents in suburban and farm communities. Plastics pipe continues to receive approval by user companies. As costs remain reasonable, quality improves, and more full pipe and fitting systems are available, even greater acceptance can be predicted for the future. 2/ With specific regard for the gas distribution application, distribution engineers want the plastic piping system to be: 1. Strong enought to conduct natural gas safely under design conditions, Z. Durable enough;:to provide long service under the normal internal and external stresses of gas distribution, 3. Flexible enough to be coiled for convenience in storage, shipping and installation, 4. Tough enough to be squeezed off for emergency service interruptions without detriment to system serviceability, 5. Resistant to chemical and physical agression of the natural environment, 6. Constituted so as not to contaminate the natural gas it conducts, 7. Readily installedand maintained, 8. Coznpatible with metal or other plastic systems already in the ground, and 9. Economical. Lone Star Gas Companies tests and experience with this system provide convincing evidence that it conforms to all the previously mentioned desires of the gas distribution engineer. What is Polyethylene? Polyethylene is one of the growing family of plastics which the chemist calls polymers. It is made from ethylene, a colorless gas produced from liquid petroleum gas, naphtha, petroleum and other naturally occurring hydrocarbon products. The ethylene molecule contains two carbon atoms joined togethe r and four hydrogen atoms, two united to each carbon atom. The two carbon atoms of the ethylene molecule are joined by a reactive bond, which enables ethylene to add to itself, in the manner of stringed beads, to form long chains called polyethylene. The.chemical process is called polymerization and the product is called a polymer. These chains are not of any definite length or shape, and a particular product (called a resin), contains chains having a range of lengths and shapes; in fact, in referring to a certain polyethylene, polymer chemists must speak of the average chain and measure the range about this average. Because of the wide geometric variations possible, polyethylenes exhibit a spectrum of properties, from lubricating greases, through high- strength structural materials, to stiff, brittle products. Only by rather precise control of the chemical reaction conditions that generate polyethylene can the resin manufacturer produce repeatedly a resin of known and useful properties. During the past decade, polyethylene manufacti'.rers have learned how to tailor-make a polyethylene for a specific job by controlling average chain lengths and shapes and their ranges. Polyethylene Characteristics The properties of a polyethylene resin depend almost entirely on' three physical characteristics: molecular weight, molecular weight dis- tribution and chain branching. A brief discussion of each parameter and its bearing on gas distribution pipe properties follows: Molecular Weight: As the reaction which produces polyethylene progresses, the chains of the mixture grow longer by addition •of successively more ethylene molecules. Molecular weight is the name polymer chemist uses to express the chain length. Although each chain has its own specific molecular weight, it is more significant to measure the average of the molecular weights of all chains in a particular resin. As the average molecular weight increases, the strength and stiffness of a polyethylene resin increase, as do its chemical resistance and' impermeability to gases and liquids. Molecular Weight Distribution: As previously stated, a particular resin will possess a range of chain lengths or molecular weights: The molecular weight distribution expresses the width of this range and under some circumstances classifies the mixture of chain lengths according to its richness in lower- and higher -molecular weight chains relative to the average. As the molecular weight distribution broadens, flexibility, toughness and stress -cracking resistance improve. Chain -Branching: Polyethylene chains tend to. grow straight, with a high degree of regularity. As the average molecular weight increases, the polymer becomes more crystalline, and its stiffness and impact sensitivity ri % increase. To eliminate these undesirable properties, the polymer chemist interrupts the regularity of chain growth by adding to the original chemical reaction mixture some heavier relatives of ethylene. By this technique, the growing chains incorporate branches, like barbs on a wire, and the crystallinity decreases without significantly affecting the molecular weight and its distribution. An appropriate increase in chain --branching confers flexibility, impact resistance and toughness, without compromising strength, chemical resistance and other properties associated with high molecular weight. The polymer chemist has developed many sophisticated techniques to measure these three physical characteristics of polyethylene. However, the quality control engineer, who wishes to know if he is feeding the pipe and fittings manufacturing plant the same resin day after clay, needs only some simple comparative tests to characterize his raw material. To check the average molecular weight, the rate of flow of the molten resin is measured while under pressure at a given temperature through a standard orifice; this measurement is called "melt index". The molecular weight distribution is checked by measuring the flow of molten plastic under several conditions of pressure and temperature. By measuring the density or specific gravity of the resin, and combining that determination with the melt index, the chain -branching of the resin is. monitored. Processing To produce pipe or tubing and fittings from polyethylene compound, the plastic is melted by heating to about 400°F, is formed in the molten • state in appropriate equipment and is cooled under controlled conditions to solidify it to the desired shape. Polyethylene is a member of the polymer family called thermoplastics, which means it can be repeatedly melted to reasonable temperatures and cooled again without destroying its properties. The thermoplastic character of polyethylene is extremely important, for it allows polyethylene to be joined to itself by heat -fusion. Conversion of raw material polyethylene to pipe and fittings is called processing. Processing is somewhat of an art, and good techniques are required to produce high-quality pipe, tubing and fittings. ASTM Requirements The A. G. A. and the American National. Standards Institute ANSI (formerly United States of America Standards Institute USASI), which publishes the B31. 8 code on "Gas Transmission and Distribution Piping Systems, " both recognize and accept the requirements of ASTM specifications as minimum qualifications for gas distribution pressure piping systems. ASTM r t D-2513-68 is therimar p y ASTM reference to polyethylene gas piping systems. This document applies to the following physical performance criteria of polyethylene pipe and fittings: 1. Long-term (ANSI B31. 8 amplifies this to include a pressure rating. ) 2. Circumferential expansion 3. Dimensions (Fitting dimensions are specified in ASTM D -2683-68T). 4. Sustained pressure test 5. Burst pressure test 6. Apparent tensile strength 7. Chemical resistance 8. Environmental stress -cracking The preponderance of the favorable experience of the natural gas industry with polyethylene pipe •for the distribution of natural gas would indicate the product could be utilized for the conveying of natural gas on the consumers premises provided the installation procedures comply with sections 842. 3 through 842. 5 of the USA Standard Code for Pressure Piping B31. 8-1968.