Back pressure valves for Chemical Injection Pumps
Back pressure valves for Chemical Injection Pumps
(OP)
For an offshore project, we have ordered chemical injection pumps and during the course of detail engineering, it was identified that for some of the injection pumps we require back pressure valves in order to avoid siphoning effect from the downstream to upstream.
The concern now is that these back pressure valves are normally constructed with the screwed housings (for piping inlet and outlet of these valves). Since this valves are going to be used for North sea offshore, NORSOK compliance is a must that does not allow screwed piping .
Client have apprehension that as these valves are of very smaller sizes, it may have vibration problem and breakage of lines and screwed joints / piping are a deviation to NORSOK
We have checked with many suppliers of these Back pressure valves but none of them are providing with the flanged body construction.
Thanks to guide whether the apprehension of the client about the small bore and vibration problems are correct and whether there are BPRs with flanged body construction?
The concern now is that these back pressure valves are normally constructed with the screwed housings (for piping inlet and outlet of these valves). Since this valves are going to be used for North sea offshore, NORSOK compliance is a must that does not allow screwed piping .
Client have apprehension that as these valves are of very smaller sizes, it may have vibration problem and breakage of lines and screwed joints / piping are a deviation to NORSOK
We have checked with many suppliers of these Back pressure valves but none of them are providing with the flanged body construction.
Thanks to guide whether the apprehension of the client about the small bore and vibration problems are correct and whether there are BPRs with flanged body construction?





RE: Back pressure valves for Chemical Injection Pumps
1) I can't work out why you want a back pressure valve in this instance. surely a non return valve would do the trick or are you actually concerned about chemicals leaking through the pump into the process when the downstream pressure is very low?
2) I've had a quick look through some relevant NORSOK standards and can't see anything about not allowing screwed pipework. Is this a misinterpretation or simply a paranoid client? Please post the spec number and clause number or ask whoever told you this to provide yu with the details. It is quite common for people to spout incorrect data they "heard from xyz" or that "they read it somewhere". If someone tells you something important like this, do a it of research yourself to see if they have actually read "Norsok" or not.
3) If the client is worried about vibration just fix the pipework down with a few more clamps. I can't see why this would vibrate anymore that f it wasn't there. dpending on your pump you could have vibration / pulsation issues, but you would need to deal with these in any case.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Back pressure valves for Chemical Injection Pumps
Yes we have also seen that there is no specific mentioning about prohibition of usage of screwed joints. But it is not listed in any of the pipe classes of NORSOK for the screwed piping / fittings. CPY has indicated that it is a deviation to L-001 as it is not listed.
But what we could see from many manufacturers of these back pressure valves, they have the screwed female connection inthe valve body and i did not see any forged flange connection ends. Should there be any specific reason for the same? may be for manufacturing and machining process?
RE: Back pressure valves for Chemical Injection Pumps
Johnny Pellin
RE: Back pressure valves for Chemical Injection Pumps
Nonetheless, you will have to comply with whatever it is the OWNER wants; regardless of Norsok, API, or anything else. Just ask the owner if the threaded connections are permissible and let him know how hard it is to find, and how expensive, to use flanged. They should have their own set of specifications for chemical injection systems. Let them make the decision; guessing and supplying something they won't allow can become expensive for you.
RE: Back pressure valves for Chemical Injection Pumps
I would ask your pump vendor if they could be of assistance. Otherwise you probably need to ask for a waiver.
+
RE: Back pressure valves for Chemical Injection Pumps
Also if you look hard enough, you can find in the valve specs some small valves with Female threaded ends (look for the "T" at the end of the valve spec. If you have threaded valves then you have to allow threaded pipe....
If CPY has a certain view about threaded joints then apply for a deviation noting that there is no such prohibition in the codes, it allows use of B31.3 and you can't find a supplier. Small components are not commercial if fitted with flanges and would weigh two or three times as much. There are issues with threaded joints on vibrating / pulsating pipework, but they can be overcome by jointing compounds, pulsation dampers and good fixing o tubing / pipework.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Back pressure valves for Chemical Injection Pumps
Part of the problem with threaded connections is the reduction in pipe wall thickness caused by cutting the threads. This can be mitigated by requiring the use of xxs pipe at the connection.
RE: Back pressure valves for Chemical Injection Pumps
RE: Back pressure valves for Chemical Injection Pumps
Thanks once again