Mechanical Engineering News SSB/SSPC                        Issue No. 4 (17 April, 1997)

Flanged Connection Gaskets Don't Take Them For Granted! by Norman Ingka EPG-MTN

No doubt more than a few of us have come across incidences where hydrocarbon was found leaking from a flanged connection, resulting in the release of HC into the surrounding environment and posing a potentially serious threat to plant safety & operations.  We have been most fortunate that no further deterioration of the condition has occurred which could have compromised our assets. What caused the leak?  The answer can be found to be one or a combination of the following possible causes:

Gasket sustained damage during storage, handling or installation due to improper operating practices. Old gasket was (re)used. Misalignment or misfit of flange mating faces. Unapproved gasket make (viz: company approved vendor list). Failure to comply with the recommended bolt tensioning values and procedures. Exceeding gasket shelf life and/or improper storage conditions. Wrong gasket material for the operating conditions. Damaged or improper flange surface preparation & cleanliness.

Within our company, there is a portfolio of standards and recommended procedures which more than adequately outline the requirements for the proper design, selection, storage and installation of gaskets.  If required, assistance from the SDE or Lead ME can be sought. Within the industry, continuous improvement, especially in gasket materials and design, is a necessity.  One particular recent improvement is in flange gaskets, where a new type design for Very Critical Service (VCS) for high pressure applications has been developed by pikotek of USA.  This new type has been reviewed and, based on proven experience at other Shell Opcos, accepted for application (MESC is now available).   It offers advantages over the conventional type gaskets in terms of higher compressive & flexural strength, metallic core with composite linings, primary & secondary seals, higher insulation, higher temperature range, lower water absorption and reuseability.  Finally, it should be noted that the pikotek VCS gaskets have been purchased for one of our new development projects.

Edited by Chris Broniarek EPO-FIP