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Preventing Bolted Flange Joint Failure

Bolted flange joints have the potential to leak, but steps can be taken to prevent this at plants and installation sites etc.


Flange joint failure regularly occurs within the Oil and Gas industry, causing millions of pounds worth of damage, therefore preventing leakages and joint failure is a main priority. In addition to carrying out regular testing procedures, consistent observations and regular maintenance is imperative to preventing failures.

An extreme example of where testing procedures failed was on an offshore platform in the North Sea. A four bolt hub joint passed the operators leak test, however, three years later an explosion occurred causing millions of pounds worth of damage.

Preventing Bolted Flange Joint Failure

An investigation took place to find the root cause, the failure was due to corrosion of a carbon steel ring which was between the two stainless steel hubs, when a stainless steel ring should have been used.

Carbon steel ring:

Preventing Bolted Flange Joint Failure

Stainless steel ring:

Preventing Bolted Flange Joint Failure

Carbon Steel vs Stainless Steel

  • Carbon steel can corrode, whereas stainless steel is protected from corrosion.
  • Stainless steel differs from carbon steel due to the amount of chromium present. Stainless steel contains a minimum 10.5% to 11% chromium amount by mass.
  • There is an in-built chromium oxide layer in stainless steel, which is not present in carbon steel.

Why Bolted Flange Joints Fail

A report was conducted into the causes of oil and gas pipeline failures in Nigeria, which showed there were five main causes of oil pipeline failures:

  • Mechanical failures (42%)
  • 3rd party activity (24%)
  • Corrosion (18%)
  • Operational errors (10%)
  • Natural hazards (6%)

Choosing the correct joint gasket type is certainly a critical decision when preventing pipeline failures as the choice is vast due to the evolution of new seal designs. Selecting the correct seal is a simple yet important design based decision and generally takes place half way through the installation process.

A study was carried out in which gaskets that were returned for repair due to leaking flanges were examined, the results found that 82% showed signs of problems due to compression, and 14% were due to the wrong product being chosen.

Incorrect compression can arise from incorrect installation procedures, misaligned flanges, incorrect flange finish and flanges that are too thin.

Preventative measures can be taken:

Whether maintenance is sub-contracted or self-maintained, research (, May 2008) highlighted the importance of training and the management of maintenance procedures. Installation guidelines, bolt tightening procedures and torque tables being issued are just the obvious main preventative measures which are simple to implement and follow.

Joint Integrity

Bolted flanges which have been installed without following the correct procedures, can have serious consequences if the joint then fails. Ensuring that the correct fitting procedures are followed, and using the correct equipment to ensure that all surfaces and connections are undamaged will assist in maintaining leak free joints.

HTL realise the consequences of leaking bolted connections, especially with numerous pipework onsite and even more connections therefore provide a full package of customer first solutions which focus on the critical elements of joint integrity including: flange surface quality, joint alignment, bolt preparation and bolt tightening.

HTL’s Joint Integrity Software packages, Joint-Pro and Bolt-Pro, are safe, secure and traceable flange management solutions. With the ability to supply the industry with premium quality products fit for specific purposes which are correctly and accurately designed and calibrated, along with an effective control process which is vital to record information, HTL have a complete package of industry leading solutions.

To get an instant quote or for further information about HTL’s premium quality solutions, contact us today: call +44 (0) 1670 700 003 or email

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