Earthing and Venting Options
EarthingTo help prevent static build up on piping systems which can result in plant explosions, an effective earthing system must be employed to make sure that all the steel piping is properly earthed. CRP have developed it’s own Spikie earthing washer for use with rotating flanges – further information can be found here. Along with these we can offer various types of earthing solutions, including welded M5 or M6 studs, carbon or stainless steel lugs etc. Typically these systems have been developed to conform to customer’s site specifications and can be applied to any of our pipe spools, fittings, sight glasses or valves. It is worth mentioning that to prevent static build up within the bores of the piping static dissipating liners must be employed too. Shown below are typical earthing stud locations, CRP recommend that the main body of a spool / fitting should have a stud / lug and any rotating flanges should have a stud / lug fitted too.
Typical earthing stud locations
Venting
Venting is required in the two key PTFE lined pipe and fittings specifications ASTM F1545
and DIN2874. There are two user reasons for venting:
First, to vent the space between liner and steelwork of any material (liquid or gas) that may collect behind the liner. Such liquid or gas build up can occur by means of
permeation through the liner. Permeation rates can be significantly affected by the choice of which PTFE or PFA to use – CRP would always recommend PFA for pipe
fittings and UltraHiPerFlon (UHP) for PTFE lined piping. However, even with such lining systems it is still necessary to guard against the effects of permeation Secondly, as an early indicator of failure. In the unlikely event of a liner failure the steel housing is likely to corrode evenly within the pipe and cause a catastrophic and unannounced failure of the complete pipe.
With a venting system, the leaking materials should show at the vent first, providing some opportunity to take the equipment out of service before massive failure. For more information please download our datasheet here.
 | Pipe spool shown here with standard welded vent boss and 65mm vent extension |
 | Welded boss, EDS PIP type vent extension complete with PTFE vent plug |
 | Vent boss with PTFE vent Plug
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Vent bosses and earthing studs can be supplied with most of our products.