Proper distance for the elbow

[estevan]

Hi!!!
We have two throttling valves for Continuous Blow Dwon station (CBD) which is between a steam drum and a blow down tank. The steam drum is pressured with 1900psig and the blow down tank vent to atmosphere.

There is elbow after the trottling valve at the CBD station.
I am looking for proper distance between the throttling valve and elbow. I worry about erosion of elbow by high pressure steam flow, but couldn't find proper information to prevent that.
I was told by Conval valves' representative that thumb of rule for the eblow distance could be 3ft per 1 inch of valve outlet diameter. My current stations have 1ft/in and there are minor erosion in the elbows.

I was wondering if one of you could tell me code recommendation or design criteria for the issue.

 

[pennpiper]

Recommendation:
1. DO NOT use elbows in Continuous Blow Down service

2. Use Pipe Bends with a radius of 5 times the nominal diameter of the pipe.

 

[MJCronin]

estevan....

What is the schedule of the piping that you are using ?

What is the material ?

Pennpiper is correct about the 5D bends, however wall thickness and material selection are also important

-MJC