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To:
Subject: Flange connection testing

Question:

My company carries out underwater oil, gas, and water injection pipeline repairs using spool piece repair connectors. For connecting the spool piece we have used 10 deg. mis-alignment flanges ( MAF’s ), which have a testing facility to test the flange joint to the desired pressure, 3375 psi ( 2250 psi. working pressure x 1.5 times ). We do this testing of the spool piece connector flange joint before actuating the Grip and Seal Connectors.

We now plan to use RTJ Flanges instead of the costly MAF's. My question specifically concerns testing of these RTJ Flange joints to the test pressure underwater without pressurizing the system, which would require actuation of the Connectors. In this regard, can you provide information as to how we can perform such a test, and whether you know of any RTJ Code specification available in any API or ASME Specification that we can use as a reference for the procurement of Connectors welded with RTJ Flanges having a seal test facility.

Answer:

We do not know of any specification or code, which covers what you want to do.

When you say you carry out underwater operations, you may mean you make-up flanges underwater. Usually, to reliably make-up RTJ flanges underwater you need to use SRX or SBX ring gaskets. We do not know of a way to test joints made-up with these “S” type gaskets without pressurizing the body of the equipment.

However, if you modify the flanges as suggested below, you can make-up the flanges underwater using R or BX ring gaskets and you can test these standard RTJ seals between flanges without pressurizing any part of the body. You will need to modify the flanges by creating a test port (typically 1/2" NPT) on the O.D. of each of the flanges that will join together. This test port must not penetrate any deeper than necessary to connect this test port to the bottom of the ring groove in each flange by drilling a 1/8" dia. hole in the bottom of each ring groove so that it intersects the test port. Leaving these test ports open during make-up underwater will vent the ring grooves of water as effectively as “S” type ring gaskets, and eliminate their need. Using the test ports after flange make-up, you can attach a test pump to the test port in each flange and apply hydrostatic pressure into the ring groove space under the gasket of the made-up connection. If pressure applied to both sides of the ring gasket seal produces no leak, you know you have a good connection seal. These tests may occur one at a time or simultaneously. In the case of certain sizes of BX gaskets that have pressure-equalizing holes drilled through, testing one port only, with the other port plugged, will test both sides of the connection. Please keep in mind that this test method described above will not work with SRX, SBX, or RX type ring gaskets.

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