we have a flanged LRC valve (size 8") being connected to high temperature and pressure urea piping. Two or three months back a consisted leakage has been started through flange connection. Any one can guide me for the possible reasons of the leakage and its remedies.

Ikram,

Gasket maybe? Need retorque of flange connection.

leem817

I think, you should have to check the flange rigidity as per Appendix 2, which should be less than one to avoid the leakage.

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Makrand Pandurang Sakpal,
Static Equipment Design,
makrands9@gmail.com,
Ph no:- 9967949656.

The flange is not a new one. It has been used for several years with no lekeage history. The leakage started after two months of being performing the turn around. PLease advice.

Ahhh... What control parameters did you specify for the re-assembly of the joint?

Many things can conspire to impede the integrity of a bolted joint. Typical "knuckle-dragging" bolting procedures such as impact-gun tightening or even "blind torquing" are leading causes of joint failure. Assuming that the joint was designed correctly and that all components are the same (albeit some such as the gaskets would be "new"), the control of the bolting process is a leading and common culprit. First question to ask: How do you know that the correct bolt load had been applied by the installation crew?

If this joint is a potentially dangerous one we wouldn't suggest that you "hot-bolt" in order to try to staunch the leak. If you have no idea what the initial applied bolt load was, any further tightening could result in yielding of the bolts or even the flanges. Once that happens, Pandora's box is breached. Best thing to do is to shut-down the process and start over. This time, ensure that you also specify a proper process QA and ensure that it's adhered to

Good luck

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"If it leaks, just give it another whack" ;-)
Global Bolted Joint Reliability Solutions