To:
Subject: Re-machining flange ring grooves.
Question:
I currently work in India refurbishing a land
rig for an Indian Oil company. The operators have had repeated
washouts of their mud pump piping flanges and have not understood
why. It seems they have put excess grease in the ring grooves
behind the gaskets, and have installed used ring gaskets into
already damaged grooves. With the information from your website I
have now educated everyone and hopefully the washouts will stop.
Can you provide some information on re-machining
corroded or washed out ring grooves?
Answer:
Shops that re-cut ring grooves should have on hand a
current copy of API 6A or ISO 10423, there they will find dimensions,
with tolerances, of seal grooves and flanges. Re-cutting of ring grooves
consists of skim cutting the face of the flange to narrow and make
shallow the existing groove so that the sides and bottom will have stock
to re-cut. Unfortunately API tolerances flanges so that manufacturers
may machine a new flange to minimum thickness, leaving no stock for
re-facing and re-cutting. In the event of no stock, shops may restore
grooves to usable condition by first filling the cleaned up (by
machining) old grooves with weld metal, stress relieving, and re-cutting
the groove.
To avoid some of this problem in the field, WOODCO
USA makes a practice of machining new flanges to the maximum thickness
allowed by API, leaving enough stock for about two re-cuts. Additionally
WOODCO USA presents the information on our Web Site to provide users
with guidance or training material so they may avoid the situation you
faced. Click here to see Field
Appraisal of Ring Grooves
Other Q & A's related to Ring Grooves and Ring
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