AMMONIA LINE

[purnawan]

I have some questions here.
1. In ammonia line ( dia 4", 6" ), is it recommended to use socket welding joint ?
2. What about inspection & test procedure ?

Best regard
Purnawan

 

[K9856]

Hi Purnawan
In general for high pressure system or piping containing hazardous material, anything above 2 inches should be butt welded. For 4" & 6" ammonia line I would say must be butt welded.
Then you should gamma-ray test it for welding quality before you pressure test it with water of low chloride content (assuming you are using stainless steel pipe for ammonia)to up to one and a half times working pressure.
This is a general procedure without knowing full details of your situation. You should check ASME B31.3 for chemical plant piping.

Paul

 

[dbevil]

AMSE B31.3 should only be used if the line is totally conatained within the boundaries of of single plant. If the line is cross-country and/or crosses public lands or roads, then the provisions of ASME B31.8 and CFR Part 192 will apply.

But I agree that any line over 2" should be butt-welded.

 

[TBP]

Ammonia piping typically falls under ASME B31.5, and is normally carbon steel. A53F pipe (usually junk to be avoided anyway), however, is expressly prohibited.

If for no other reason, economics dictates butt welds in larger diamter pipe. 2" pipe is the typical upper threshold for socket welding.

Many plants (most of my experience involves food processing operations) avoid hydrostatic testing of ammonia systems, and use pneumatic. This is because even trace amounts of moisture in these systems will cause operational problems due to ice crystals forming.

 

[MJCronin]

purnawan,

Go with the experience of the ammonina manufacturers and distributers.

Most of what is said above is valid,... however check the following website and ask LaRoche specific questions about your storage/transfer systems

http://www.larocheind.com/

ASME B31.3 is the appropriate piping code; butt welded fitting are best above 2"NPS.....avoid water in piping systems.

let us know what you decide..........


MJC

 

[TBP]

MJC - Applicable code depends upon the jurisdiction and plant. In Ontario, unless the NH3 piping is in a petro-chem, pulp & paper mill, etc, it very much WILL be deemed to fall under ASME B31.5. Always check with the local inspection authority.