×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Pressure Balance hole in ball Valve

## Pressure Balance hole in ball Valve

(OP)
As per API 6D 25th Edition, the design of the pressure balance hole, when equipped, shall have a ratio between the length of the hole
and the hole diameter of less than 10 (L/D < 10).

How / Why this ratio is provided ?

### RE: Pressure Balance hole in ball Valve

The intention was to minimize the risk of the hole getting plugged and then no longer providing the pressure balance functionality during service. A hole with a high L/D ratio is more susceptible to plugging due to fouling.

The specific ratio (L/D < 10) was arbitrarily chosen.

The 6D task group has recognized that this could result in undesirably large pressure balance hole diameters on large valves. There is an addendum in progress (planned to go to ballot this week) that would limit the maximum required hole size to 0.5".

### RE: Pressure Balance hole in ball Valve

Just a thought, if you need a smaller diameter but have a long run, could you use a stepped hole so that at no point it would violate the rule?

So instead of a hole 6" long x .5" diameter L/D = 12 you could have a first hole 3" long x 1" diameter L/D = 3 and a second hole 3" long x .5" diameter L/D = 6.

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!