Interpretation Response #PI-77-023

Interpretation Response Details

October 18, 1977

Mr. Bob Pourchot
Product Engineer
Central Plastics Company
P.O. Box 762
Shawnee, OK 74801

Dear Mr. Pourchot:

Your letter to Mr. Paul Cory requests that we review the design of the anodeless service riser manufactured by Central Plastics Company and determine if it violates the requirements of the Federal gas pipeline safety regulations, 49 CFR Part 192.

The Office of Pipeline Safety Operations (OPSO) does not approve, endorse, or make the requested determination on proprietary items. We can, however, discuss the design and indicate the requirements that would be applicable.

You previously supplied Mr. Cory with drawings of the service riser in question that show the transition from plastic to metal pipe occurring belowground. This transition is enclosed in a metallic casing that extends belowground over the plastic pipe and upward over the steel gas pipe to a point below the threaded upper end of the service riser. The steel gas pipe and the transition fitting are insulated from the casing by a combination of polyethylene tubing and epoxy materials.

These plastic materials fill the void between the steel gas carrying pipe and the casing and since the plastic is not carrying gas, it is not subject to the temperature limits of Section 192.123.

Also, according to the design provided to OPSO, the steel gas carrying pipe that extends from belowground to the head of the service riser is enclosed in a covering of plastic material which in turn is covered by the steel casing. Plastic material fills the void between the casing and carrier pipes and is intended to insulate the carrier pipe from the casing. If it can be shown under Section 192.455(b) that the steel gas pipe is in a location where a corrosive environment does not exist, then cathodic protection would not be required.

Thank you for your interest in pipeline safety. If you have additional questions, please advise.

Sincerely,

'signed'

Cesar DeLeon
Acting Director
Office of Pipeline
Safety Operations

Regulation Sections