Help with liquid NH3 Line Stop

[seasar]

I'm taking a guess that some viewers of this forum may
work in chemical manufacturing facilities that have had the need to do line stops in the past.

I'm hoping to get recommendations on companies that perform this service...my need is for a line stop in a liquid anhydrous ammonia line. We've done this in the past and the company we've used, while competent, was a little too risk happy. I'd like to feel out other companies...trying to find the gold standard.

Thanks,

 

[ash9144]

I assume by line stop you mean plugging a pipe that is leaking to the atmosphere.

This is common reaction. Contractor company A comes in does a poor job. Switch to contractor company B.
This is wrong. Responsibility for the contractor is the parent company's responsibility. Understand and know how they want to proceed with a task then you tell them how you want it to proceed. If you can't agree then find another company. If you agree you must then supervise their work and ensure they comply with the standards you set.

You can switch "companies" and have the exact same workers show up at your facility.

 

[seasar]

By line stop I mean cutting into a line while it is in service to insert a plug in order to replace a downstream isolation valve that is no longer sealing.

 

[unclesyd]

You didn't mention any sizes or pressure. There is a specific lower limit on line sizes.

I have to disagree with part of the post by ash9144 about telling a hot tap company how to proceed. Unless one is well versed in the art and science of this process it is better left to the experts. I not saying leave them alone to do their thing you can still ask questions about their procedure and discuss your concerns especially the safety aspect. The secret of getting a sound and safe job is to work with the companies that have been around for a while. Another point is that you need to have your ducks in row and convey all the needed physical data up front. The crews that are doing the actual work may or may not be able or willing to change their procedures. You need to have your contingencies planned out for such things as breakdowns of equipment, process upsets while hot tapping, etc.

Here is a short article on the genral aspects of hot tapping and line stopping.

http://www.ceejpublishing.com/Articles/0009.htm

You need to look at Team's capability very closely.

http://www.teamindustrialservices.com/taps/default.html

TD Williamson has been around a long time and has seen and done it all.

http://www.tdwilliamson.com/new_servtdw/tdwservices.html

We have close to a millon pounds of ammonia in circulation in our process everyday and I've never seen any problems with valves other than packing leaks in 50 years.

 

[unclesyd]

Forgot to add this page. As stated this maybe the way to go if your line size is under 4".

http://www.teamindustrialservices.com/taps/bolt_on_fittings.html