ASME B16.40 pdf download MANUALLY OPERATED THERMOPLASTIC GAS SHUTOFFS AND VALVES IN GAS DISTRIBUTION SYSTEMS
1.2 Quality Systems
Nonmandatory requirements relating to the productmanufacturer’s Quality System Program are describedin Appendix A.
2 cONSTRUCTION2.1 General
(a) The workmanship employed in the manufactureand assembly of each valve shall provide gas tightness,safety and reliability of performance, and freedom frominjurious imperfections and defects.
(b) Design details not addressed in this Standard arethe responsibility of the manufacturer.
2.2.1 Valve Shell Parts. Pressure-containing valveshell parts shall be made from materials specified inand qualified to the requirements for pipe and fittingsas listed in ASTM D 2513,Specifications for Thermo-plastic Gas Pressure Pipe，Tubing and Fittings.Otherthermoplastic materials may be used for such partsprovided they satisfy the following requirements fromAppendix Xl of ASTM D 2513:
(a) an ASTM material specification,and
(b) a long-term hydrostatic-strength，determined inaccordance with an appropriate test method such asTest Method D-2837.
In addition,evidence shall be presented to demon-strate that such materials will perform satisfactorily infuel gas environments as listed in para. 1(c).
2.2.2 Parts Other Than Valve-Shell Parts. Partsother than shell parts, which contribute to pressurecontainment or to retaining differential pressure acrossthe closure element，shall be resistant to the gases inpara. 1(c). Such parts shall be designed to withstandnormal valve-operating loads and, in addition,shallprovide long-term pressure-containment integrity con-sistent withvalve-shell parts. The sustained pressuretests of paras. 3.3.3(a) and 3.3.3(b) shall qualify thematerial selections for these parts，which include，butare not limited to, the closure member，stems or shafts(if they are designed to retain pressure), and fastenersretaining shell sections.
2.2.3 Lubricants and Sealants. Lubricants andsealants shall be resistant to the action of gases referredto in para. 1(c).
2.2.4 Responsibility. When service conditions,such as gases having high hydrogen content or com-pounds likely to form condensate,dictate special materi-als considerations,it is the users’responsibility tospecify this information to the manufacturer.
2.3.1 Operating Indication
(a) Valves designated for one-quarter turn operationshall be designed to visually show the open and closedposition of the valve. A rectangular stem head or anarrow thereon or a separate position indicator shallindicate the closed position of the valve port when thelongitudinal axis of the stem head or indicator isperpendicular to the axis of the connecting pipe. If aseparate indicator is employed,it shall be designedsuch that it cannot be assembled to incorrectly indicatethe position of the valve.
(b) Valves designed for more than one-quarter turnoperation shall close by clockwise stem rotation, unlessotherwise specified by the user. The direction for closingthe valve shall be indicated.
2.3.2 Valve End Design. Valve ends shall bedesigned to one or more of the following, unlessotherwise specified by the user:
(a) polyethylene valve stub-ends that conform to theapplicable dimensions listed in Tables 1，2,and 3 ofASTM D 3261;