Notice No. 16
July 10, 2000
RUPTURE OF SOUR GAS PIPING
A section of gas piping ruptured on a Pacific OCS Region platform,
releasing natural gas containing hydrogen sulfide (H2S). The platform was immediately shut
in, personnel went to their designated safe briefing areas, and no one was injured.
However, there were some minor irregularities in the personnel response to the H2S
release. In addition, ultrasonic testing of the process piping had been performed about a
week prior to the accident, and the test results had shown serious corrosion in the
vicinity of the ruptured elbow; no corrective action was taken by the platform operator.
MMS regulations pertaining to H2S are at 30 CFR 250.417. The regulatory sections relevant
to our accident investigation findings are excerpted below. They are followed by measures
that the MMS is recommending in the interest of safety.
According to 30 CFR 250.417(j)(5)(ii), operators of platforms that produce sour gas "…must
have a sensor in buildings where personnel have their living quarters." Based on
our accident investigation, we recommend that such operators ensure that the air inlet H2S
detection devices for the living quarters are tested regularly.
According to 30 CFR 250.417(h)(1)(i), H2S drills must be performed "…for
each person at the facility during normal duty hours at least once every 7-day
period." Based on our accident investigation, we recommend that operators
emphasize familiarity with the locations and use of all the breathing equipment on the
platform during these drills, in addition to covering the other important aspects of H2S
contingency planning.
Under 30 CFR 250.417(q)(7), Corrosion Mitigation, operators "…must use
effective means of monitoring and controlling corrosion caused by acid gases (H2S and CO2)
in both the downhole and surface portions of a production system. You must take specific
corrosion monitoring and mitigating measures in areas of unusually severe corrosion where
accumulation of water and/or higher concentration of H2S exists." Based on our
accident investigation, we recommend that operators consider taking the following steps
with regard to ultrasonic testing (UT):
- Perform periodic UT on piping, especially those carrying corrosive and
toxic products. The American Petroleum Institute’s API 570, Piping Inspection
Code: Inspection, Repair, Alteration, and Rerating of In-Service Piping Systems
contains relevant information.
