California Code of Regulations
Title 8 - Industrial Relations
Division 1 - Department of Industrial Relations
Chapter 4 - Division of Industrial Safety
Subchapter 1 - Unfired Pressure Vessel Safety Orders
Article 7 - Compressed and Liquefied Natural Gas System
Section 526 - Repairs and Alterations to Tanks, Welded Piping and to Welded Vaporizers Having a Volumetric Capacity in Excess of 1 U. S. Gallon

(a) No repairs or alterations involving flame, arc or other method of welding shall be made on any tank, vaporizer or piping unless such tank, vaporizer or piping shall first have been certified as natural gas free or oxygen free by competent personnel.

(b) No repair or alteration to a natural gas tank or welded vaporizer which affects the safety of such natural gas tank or welded vaporizer shall be made until the contemplated repair or alteration has been authorized by a qualified inspector. The exchange or interchange of valves, fittings and accessories intended for the same purpose need not be considered a repair or alteration.

(c) No tank, vaporizer or piping system that has been subjected to possible damage by fire shall be returned to service until it has been inspected by a qualified inspector and found to be safe.

(d) Any vessel, vaporizer or piping requiring repair or alteration or that has been subjected to a fire shall be prepared for hydrostatic test by the owner when such test is deemed necessary by the qualified inspector.

(e) No repairs shall be performed on any natural gas fueled motor vehicle nor on a transport tank, trailer or skid tank, whether empty or loaded, until reasonable precaution has been taken to provide the required safety.

(f) All repairs to natural gas tanks or vaporizers affecting the safety of such tanks or vaporizers shall be reported to the Division within 21 days by the qualified inspector authorizing such repairs. The qualified inspector shall stamp his certificate of competency number adjacent to all welded repairs authorized by him except that in the case of repairs to quenched and tempered steels, this number need not be stamped. This exception shall be noted in the inspector's report.

(g) Any welding necessary when making repairs or alterations to tanks, vaporizers or piping shall be done according to welding procedures and by welders qualified in accordance with the rules of Section IX of the ASME Code in the position or positions used in making the repair.

(h) Repairs to DOT cylinders shall be made under DOT regulations and control.