Installing Weldolets on an Existing Pipeline

[masao777]

I will install two weldolets 2" on a 20" existing gas pipeline for temperature and pressure devices using a hot-tap process.

I know for sure that the nipple plus one flange need be hydrotested with 1.25 MAOP of the pipeline and not 1.25 MOP of the pipeline, or RX will be enough in the weld joint will be enough?

I know that valve is not necessary to be hydrotested, because this has the certificates?

I am not sure if the distance between both weldolets are limitated to two diameters of the main pipeline or not?

I will apply RX in the welds joints of the weldolet to nipple and nipple to flange and ink penetrant for the weld joint of weldolet and pipeline, or I need other testing methos?.

Do you have some comments??

 

[pennpiper]

You wrote:
"I am not sure if the distance between both weld-o-lets are limited to two diameters of the main pipeline or not?"

Two diameters is not mandatory but I would make sure I had some off-set between the two. I would also make sure that I installed the PI up stream of the TI so the "Wake turbulence" from the well did not affect the PI reading.

You wrote:
"I will apply RX in the welds joints of the weld-o-let to nipple and nipple to flange and ink penetrant for the weld joint of weld-o-let and pipeline, or I need other testing methods?"

The proper term is RT (not RX). RT is normally only recognized as an appropriate way to examine a Butt Weld. It is not reliable for fillet welds used for an O-Let fitting welded to the pipe or for Socket Weld fittings.

Why are you adding a nipple between the Weld-O-Let and the Weld Neck Flange. Is it possible you are actually using a Sock-O-Let and a Socket Weld Flange?

 

[masao777]

pennpiper,

Thanks, and I am from Argentina, so sometimes my English make mistakes writing RX instead RT, but we are in same concept.

I am agree, with you comment of up-stream, and we have enogh space to separate the connections two diameters.

I know that the RT is for butt welds and not for weldolets, so that is why I will use only for the joints of weldolet to nipple and nipple to flange. You idea is good to use sockolet and socket weld flange, because we will avoid money doing RT.

I am agree with you to avoid the nipples, but that should be if we are using weldolet and a flange WN, but if we are using sockolet and a socket weld flange, we need a nipple to connect them.

What about the Hydrotest, because if we make ink penetrant testing for the filled welds, and if we have all certificates for the flange, sockolet and valve, I don't see necessary to make hydro-test.

But under ASME is indicated the hydro-test!, so it is not clear is it is recommendatory or mandatory practice?.

 

[masao777]

pennpiper.

My pipeline has a MAOP of 4609 psig, so that is why I prefer to use butt weld joints, even the weld between the weldolet and the nipple or flange will not be butt weld. I feel more comfortable using butt weld joints in all places I can do it, instead lapped or filled joints. What you think?

 

[BigInch]

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[pennpiper]

I recommend that you do the proper NDE (VT, PT, RT) and then do a Hydrotest.