PTFE & PFA ​Installation Procedure

When using smooth-running and greased bolts and nuts we recommend the tightening torques in the table below:

For pressure rating Class 150

 InchBoltsTightening torgues
1/2”4 x 1/2”25
3/4”4 x 1/2”25
1”4 x 1/2”30
1 ½”4 x 1/2”60
2”4 x 5/8”80
3”4 x 5/8”120
4”8 x 5/8”70
6”8 x 3/4″130
8”8 x 3/4”180
10”12 x 7/8”190
12”12 x 7/8”240

For pressure rating Class PN10/16

 DNBoltsTightening torgues
254 x M1230
404 x M1660
504 x M1680
654 x M16100
804 x M1660
1008 x M1670
1258 x M1690
1508 x M20130
2008 x M20180
25012 x M20160
30012 x M20210

1. Tightening the bolts:

  • Insert the washers
  • Clean and grease bolts
  • Tighten nuts by hand
  • We have taken a friction coefficient of 0.14 (f=0.14) in account.
  • Tighten each bolt using a torque wrench, keeping to the torque values specified in the table.
  • The torque wrench should be used in a cross manner.
  • If a flange connection leaks, despite the fact that all bolts are tight, do not tighten further. Loose the connection, inspect the seal face and re-install.


2. Gaskets

It is a must to use MB-SURELINE® Fluor gaskets between the flange connection. They are special designed for PTFE/PFA lined piping systems.


All information and data quoted are based upon years of experience in the production and operation of sealing elements. This data may not be used to support any warranty claims. With its publication this latest edition supersedes all previous issues and is subject to change without further notice.


See Our PTFE & PFA lined pipe and fitting products