Branch connection at Tee 1

[mechpiper]

We have a existing 36"NB LNG header and as part of the modifications to the pipework we need to have 16" branch connection on this line. Due to the layout constraints only possible location to have the bracnh is at a butt welded Tee.(See sketch attached). I am trying to find the code requirement on this type of connection and the restriction on the angle theta. (can it be 90 deg. or 45 deg.?). Piping is designed as per ASME B31.3

 

[pennpiper]

Mechpiper,

Existing - 36"NPT
Branch - 16" NPT
Material - (Not given)
Wall Schedule of existing Tee - (Not given)
Age of existing system - (Not given)
Commodity - LNG
Maximum Operating Pressure - (Not given)
Maximum Operating Temperature - (Not given)

It is kind of hard for anyone out here to offer any help when so much information is missing.






prognosis: Lead or Lag

 

[mechpiper]

Pennpiper

Apologies for the lack of info on my first post. I wanted to check conceptually if it was workable.
It would be a great help if you can point me to the code reference.

The missing info.

The Piping material : A358 Grade 304
Wall thickness of existing tee : 0.5"
Age of system : ~25 years (was put on standby for approx 5 yrs during this period)
Max. Operating Press/Design Pressure : 80psi / 220 psi
Min operating temperature : -260 deg. F

Thanks

 

[pennpiper]

Mechpiper,
You wrote:"I wanted to check conceptually if it was workable.
It would be a great help if you can point me to the code reference."

1). Yes it is conceptually workable
2). There are some things the Codes do not address. They do not say you can do it and they do not say you cannot do it.
3). Since the system is 25 years old and has been idle for 5 years I recommend you do some ultrasound examinations to determine remaining wall thickness.
4). Purchase a 36" x 16" WOL to weld to the Tee plus a 16" Flange.
5). You might want to consider getting a reliable "Hot-Tap" contractor to do the connection.
6). Have the "Hot-Tap" contractor weld the O-Let & Flange to the Tee at the required angle.
7). Install a Blind Flange to the Connection and Hydrotest the Branch. The Blind will need taps fot adding and draining the Hydrotest water.
8). When the Hydro is successful then have the Hpt-Tap contractor cut out the coupon.

Just my suggestions.


prognosis: Lead or Lag

 

[davefitz]

I am not sure where you will find a welder to add a hot tap on an LNG line, maybe the Tea party?

Considering the potential hazard with LNG, it might be recommended that someone with a little more experience be assigned this project.

 

[pennpiper]

As said in my comment #5 above:
"5). You might want to consider getting a reliable "Hot-Tap" contractor to do the connection."

prognosis: Lead or Lag