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Buried Insulating Joint 6

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McDermott1711

McDermott1711

Mechanical
Nov 17, 2010
318
Have you ever seen buried Insulating Joint?
Client asked it in order to have his buried gas pipeline potentially isolated from new buried branch.
Is it allowable to bury it? If so, is it effective underground?
 
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Yes, yes and yes. Typically you will have test wires coming up above grade to a post.
 
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Yes, I've seen them buried and yes you can bury them.

Is it a good idea - not in my opinion as you can't see any leakage and unless the branch is also cathodically protected, it can suffer increased corrosion risk if there is current leakage from the main pipe and any coating damage on the branch pipe. It is also harder to calculate and restrict bending stress on buried tees which can overstress your IJ quite easily.

I don't really understand the clients concern though.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way
 
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Yes, bury them all the time. Note that lightning strikes can damage them, so you may want to consider installing a spark gap surge arrestor in parallel to the insulating joint.
 
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austsa (Mechanical) said:
Yes, bury them all the time.
Click to expand...
But in case of A/G to U/G pipeline, I've seen a lot of insulation joints which are not buried.
 
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Just 'cause you've seen it doesn't mean it's a good way to do it.

I've even seen launcher and kicker valves that aren't buried... and doubled trap isolation valves, double kicker valves, even on the vents, and pig launchers located so close to the center of the plant facilities that somebody thought they needed a blast wall between the launcher opening and plant piping so it would be safe. Get that... "be safe" ???

Personally I think doubled valves over-complicate the launching procedures so as to make them actually more unsafe ... except maybe in the case of poisonous gases I would use ONE double-block & bleed valve. Trying to remember to close 2 valves here, two valves there... and the first thing that happens is that when the pig gets stuck, they just open both of them. Too much work... next time they'll only close one, then the guy coming along expecting to see both of them closed ... oh oh.

There's a lot of ways you can skin a cat, but most of them ... not good.

Independent events are seldomly independent.
 
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"I've even seen launcher and kicker valves that aren't buried..."

What client do you work for that ALLOWS you to bury valves?!

"... I would use ONE double-block & bleed valve"

So which kind of single piggable valve would you use for this? Good ol' slab gates are NOT DOUBLE ISOLATION & BLEED (see latest API 6D) valves that meet most current pipelines safety specs.
 
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Well pipelines are mostly underground, so it's better not to come up out of the ground just to set a valve up in mid air.
I can post a kml file where you can zoom in on them and see the hand wheels sticking out of the ground. There must be millions of buried valves on pipelines. I would never use a gate valve on a launcher, takes too long to operate them and you just might slice a pig in half. :) Use 1/4 turn double block and bleed BALL valves. But if you absolutely want to have a double block and bleed gate valve.... here it is,




Independent events are seldomly independent.
 
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a bit off topic here, but I've seen both. For systems in the middle of the pipeline, buried valves are common place. For the main line valves inline, I personally would not consider a ball valve to be capable of DBB as single item. Other connections you can use other types of valves which give you true DBB.

The WKM valve is one of the best I've ever used in pig trap or isolation usage and works very well.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way
 
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it seems the subject was Insulating Joint, but good debate about valves. Meanwhile, I found out two spec, one of them asked that I.J.s to be installed in vertical position so that possibility of conducting settlements became minimized but the other (better one) wanted to have interior surface of I.J.s being coated.
 
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You need to be quite careful about internal coating. If you get a small hole in the earthed side of the IJ with a conductive fluid, it will bore a hole right through as though it had been drilled. Given IJs are normally in piggable pipelines, internal coatings can get damaged. Some operators now don't use monolithic IJs with conducting fluid but insualting flanges and "sactrifical" thicker spool pieces on the earthed side of the flange.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way
 
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Ya. Sometimes you gotta pick up the phone.

Any way... another great reason to put IJs on the opposite side of the trap from the pipeline being pigged!!!

Independent events are seldomly independent.
 
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Thanks LittleInch for your advice. BTW, do you have any link to a vendor for "non-monolithic" IJ?
 
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NACE SP0286 would make a good read for this question. Another method of dealing with a conductive fluid is to have an isolating spool with insulating flange kits at both ends and a high quality thick film coating on the inside. It then becomes a case of how long should the spool be. Some basic electrical resistance calculations can be used to take a stab at deriving a spool length. This assumes that the HSE case is happy to see multiple flanges introduced into the system.

Steve Jones
Corrosion Management Consultant


All answers are personal opinions only and are in no way connected with any employer.
 
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HI everyone
I'm new in the fórum, and kind of lost. Don't know where to find the topic I'm interested in. I'd appreciate if someone gives me some guide. I have to design a cathodic protection system for buried pipelines. What could I read about this, what codes??
 
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So, a skilled CP engineer given a task within their competence then?

You can read the following:

NACE SP0169
ISO 15589-1
Peabody's Control Of Pipeline Corrosion

oh, and you could try using the search posts box to the top right


Steve Jones
Corrosion Management Consultant


All answers are personal opinions only and are in no way connected with any employer.
 
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