Part 255 Transmission and Distribution of Gas

(a) Each underground vault or closed top pit containing either a pressure regulating or reducing station, or a pressure limiting or relieving station, must be sealed, vented or ventilated. (b) When the internal volume exceeds 200 cubic feet (5.66 cubic meters), each of the follow…

(a) Each vault must be designed so as to minimize the entrance of water. Nevertheless, vault equipment shall be designed to operate safely, if submerged. (b) A vault containing gas piping may not be connected by means of a drain connection to any other underground structure. (c) …

(a) Unmanned structures housing calorimeters or calorimixers shall be designed so that the egress shall be directly to and from the outside, and all air movements shall be directly to and from the outside atmosphere. All associated devices which may vent gas shall be vented throu…

(a) The design pressure of polyvinyl chloride (PVC) Schedules-40 and 80 thermoplastic fittings must be obtained from the following table: These pressure ratings are the same value as the design pressure of the corresponding pipe size and schedule in the same class location, as de…

Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve or shut-off is operated, and from any other secondary stresses that might be exerted through the valve or its enclosure.

Sections 255.195 through 255.203 of this Part prescribe the minimum requirements for the design and installation of overpressure protection devices.

(a) Except as provided in section 255.197 of this Part, each pipeline that is connected to a gas source so that the maximum allowable operating pressure could be exceeded as the result of pressure control failure or of some other type of failure, must have pressure relieving or p…

(a) If the maximum actual operating pressure of the distribution system is 60 psig (414 kPa) or less and a service regulator having the following characteristics is used, no other pressure limiting device is required. (1) The regulator is capable of reducing distribution line pre…

(a) Except for rupture discs, each pressure relief or pressure limiting device must: (1) be constructed of materials such that the operation of a device will not be impaired by corrosion; (2) have valves and valve seats that are designed not to stick in a position that will make …

(a) Except where otherwise indicated, this Part will not be applied retroactively to existing installations insofar as design, fabrication, installation and testing are concerned. (b) However, all the provisions of this Part will be applicable to any recertification, upgrading, o…

(a) Each pressure-relief or pressure-limiting station or group of stations installed in a low pressure distribution system must have enough capacity, and must be set to operate, to ensure that the pressure may not cause the unsafe operation of any connected and properly adjusted …

(a) This section applies to the design of instrument, control, and sampling piping and components. It does not apply to permanently closed systems, such as fluid-filled temperature-responsive devices. (b) All materials employed for pipe and components must be designed to meet the…

(a) Sections 255.225 through 255.245 of this Part prescribe minimum requirements for welding steel materials in pipelines. (b) These sections do not apply to welding that occurs during the manufacture of steel pipe or steel pipeline components.

(a) Welding must be performed by a qualified welder or welding operator in accordance with welding procedures qualified under section 5, section 12, Appendix A or Appendix B of API Standard 1104 (as described in section 10.3 of this Title), or section IX of the ASME Boiler and Pr…

(a) Except as provided in subdivision (b) of this section, each welder or welding operator must be qualified in accordance with section 6, section 12, Appendix A or Appendix B of API Standard 1104 (as described in section 10.3 of this Title), or section IX of the ASME Boiler and …

(a) No welder or welding operator whose qualification is based on nondestructive testing may weld compressor station pipe and components. (b) No welder or welding operator may weld with a particular welding process unless, within the preceding six calendar months, he has engaged …

(a) Each operator shall conduct an unannounced spot check of each welder's field welds at least once each calendar year to assess the quality of welding. Such spot checks shall include destructive or nondestructive tests of a field weld. Should an unannounced spot check of a weld…

The welding operation must be protected from weather conditions that would impair the quality of the completed weld.

(a) A miter joint on steel pipe to be operated at a pressure that produces a hoop stress of 30 percent or more of SMYS may not deflect the pipe more than three degrees. (b) A miter joint on steel pipe to be operated at a pressure that produces a hoop stress of less than 30 percen…

(a) Before beginning any welding, the welding surfaces must be clean and free of any material that may be detrimental to the weld, and the pipe or component must be aligned to provide the most favorable condition for depositing the root bead. This alignment must be preserved whil…

(a) Visual inspection of welding must be conducted by an individual qualified by appropriate training and experience to ensure that the welding is performed in accordance with the welding procedure and the weld is acceptable under subdivision (c) of this section. (b) The butt wel…

(a) Nondestructive testing of welds must be performed by any process, other than trepanning, that will clearly indicate defects that may affect the integrity of the weld. (b) Nondestructive testing of welds must be performed in accordance with written procedures and by persons wh…

(a) No person may carry out the inspection of joints in welded pipelines required by sections 255.241 and 255.243 of this Part unless that person has been qualified by appropriate training or experience in evaluating the acceptability of welded joints per the requirements of sect…

(a) Each weld that is unacceptable under section 255.241(c) must be removed or repaired. A weld must be removed if it has a crack that: (1) is more than eight percent of the weld length or two inches (51 millimeters) in length whichever is less; or (2) penetrates either the root …

(a) Sections 255.273 through 255.287 of this Part prescribe minimum requirements for joining materials in pipelines, other than by welding. (b) These sections do not apply to joining during the manufacture of pipe or pipeline components.

(a) The pipeline must be designed and installed so that each joint will sustain the longitudinal pullout or thrust forces caused by contraction or expansion of the piping or by anticipated external or internal loading. (b) Each joint must be made in accordance with written proced…

(a) Copper pipe may not be butt welded or threaded, except that copper pipe used for joining screw fittings or valves may be threaded if the wall thickness is equivalent to the comparable size of standard wall pipe. (b) The filler material used for brazing shall be a copper-phosp…

(a) A plastic pipe joint that is joined by solvent cement, adhesive or heat fusion may not be disturbed until it has properly set. (b) Plastic pipe may not be joined by a threaded joint or miter joint. (c) The quality of the joints shall be checked visually. If there is any reaso…

Before any written procedure established under section 255.273(b) of this Part is used for making plastic pipe joints by a heat fusion, solvent cement, or adhesive method, the procedure must be qualified by subjecting specimen joints that are made according to the procedure, to t…

(a) No person may make a plastic pipe joint unless that person has been qualified under the applicable joining procedure by: (1) appropriate training or experience in the use of the procedure; and (2) making a specimen joint from pipe sections joined according to the procedure th…

No person may carry out the inspection of joints in plastic pipes required by sections 255.273(c) and 255.285(b) of this Part unless that person has been qualified by appropriate training or experience in evaluating the acceptability of plastic pipe joints made under the applicab…

(a) As used in this Part: (1) Abandoned means permanently removed from service. (2) Abnormal operating condition means a condition identified by the operator that may indicate a malfunction of a component or deviation from normal operations that may indicate a condition exceeding…

Sections 255.302 through 255.327 of this Part prescribe minimum requirements for constructing transmission lines and mains.

(a) At least 30 days prior to the start of construction or reconstruction of any transmission line or main designed to operate at 125 psig (862 kPa) or more, each operator shall file a letter of intent and a report of specifications identical with Form A of Appendix 7-D of this T…

All construction work performed on piping systems in accordance with the requirements of this Part shall be done under construction standards which shall be readily available for inspection by the department. The construction standards shall cover all phases of the work and shall…

(a) Each transmission line and main must be inspected during construction to ensure that it is constructed in accordance with this Part. (b) Inspections shall be made at sufficiently frequent intervals to assure the required quality of workmanship. (c) Inspectors shall be qualifi…

Each length of pipe and each other component must be visually inspected at the site of installation to ensure that it has not sustained any visually determinable damage that could impair its serviceability. These inspections must be made: (a) prior to the coating operation for fi…