Interpretation Response #PI-71-0114

Interpretation Response Details

Fluor Ocean Services, Inc.
Engineers Constructors
P.O. Box 36878 6200 Hillcroft
Houston, Texas 77036

June 2, 1971

Office of Pipeline Safety
Department of Transportation
400 Sixth Street, S.W.
Washington, D.C. 20590

Attention: Mr. Joseph C. Caldwell Acting Director

Dear Sir:

We have recently installed a blow-down flare system for Michigan- Wisconsin Pipe Line Company on their juncture platform located in Eugene Island Block 188, Offshore Louisiana. I have discussed this installation with Mr. Joseph de la Fuente of your Houston office, and he in turn has discussed it with Mr. Peter Kuh in Washington.

The flare provides a means for blowing-down the various Michigan- Wisconsin offshore pipelines that come together at this platform. The flare is isolated by manually operated valves from each of the pipelines that it serves. Additionally, there is an automatically operated pressure control valve located at the inlet to the flare line to properly monitor flow to the 36-inch diameter flare tip, and this controller is designed so that it will "fail-closed" in the remote event of accidental over pressuring of the flare line.

The question has been raised as to whether a pressure test is required of the flare line down stream of the pressure controller. In my discussions with Mr. de la Fuente he said that his interpretation of Paragraph 192.179(c), ("Each section of a transmission line, other than offshore segments, between main line valves must have a blow-down valve...") did not require a blow-down for offshore installations, and therefore a pressure test of this blow-down system cannot be required.

Can you please give us your interpretation of this section of the regulations. An early reply would be appreciated as Michigan-Wisconsin wishes to put the line in service soon.

Yours very truly,
FLUOR OCEAN SERVICES, INC.
K. B. Lindsby

PI-71-0114

June 23, 1971

Mr. K.B. Lindsey
Fluor Ocean Services, Inc
Engineers Constructors
P.O. Box 36878
Houston, TX 77036

Dear Mr. Lindsey:

This is in reply to your letter of June2, 1971, concerning the application of Section 192.179 of the Federal gas pipeline safety standards, to a blow-down flare system on and off-shore platform in the Gulf of Mexico.

The system, as you have described it, is not a pressure containing part as it is open at the end and there is no way for pressure to be contained in the blow-down. Therefore, the blow down flare system downstream of the pressure controller does not require a pressure test.

It is true that §192.179 exempts offshore segments of transmission lines from having a blow-down valve. However, any component or associated piping that is part of a pipeline as defined in §192.3 (i.e. gas moves in transportation) must be designed, constructed, tested, operated and maintained in accordance with the applicable regulations even though the segment is not required by the regulations to be installed.

If we can be of any further assistance, please let us know.

Sincerely,
Original singed by:
Joseph C. Caldwell
Acting Director
Office of Pipeline Safety

Regulation Sections