Spectacle Bilnds
Spectacle Bilnds
(OP)
is it more common to have spectacle blinds made from plate or have them forged. We have some that are 16" Class 600. Also, what about a raised face or not?
thanks
mark
thanks
mark
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Spectacle Bilnds
Here's what we use to make.
Greetings
RE: Spectacle Bilnds
thanks again
mark
RE: Spectacle Bilnds
And why then?
RE: Spectacle Bilnds
It is my understanding that spec blinds are not to be used for hydros for the distinct purpose that they might not meet the flange ratings of testing. Thicknesses of spec blinds are not the same as testing blinds. Spec blinds are used for blanking off lines for work down stream of lines. Maybe this will answer some things. Correct me if I am wrong.
Eric
RE: Spectacle Bilnds
If you go by that standard then acceptable materials are per B16.5 Table 1A which includes plate materials.
From 3.3.1, A raised face may be specified at the option of the purchaser.
Ratings are per B16.5. As for hydrotesting, 2.2.2 states that Line blanks may be subjected to system tests at a pressure not to exceed 1.5 times the 38°C (100°F) rating rounded off to the next higher 1 bar (25 psi) increment... So it would appear that the blinds (if B16.48 compliant) are considered to be adequate for hydrotests.
jt
RE: Spectacle Bilnds
Spectacle blinds are calculated and used for full press.requirements and spades are used for seperations of systems for whatever reasons.
Greetings
RE: Spectacle Bilnds
This spectacle blind is in a 16" line and is a Class 600 system. It is part of a depressurization system and the blind is used only for hydro-testing purposes. Seems like an expensive setup (2 16"CL600 stainless RFWN flanges, hardware, and the blind) for just a single use.
RE: Spectacle Bilnds
You may calculate to use carbon steel plate for hydrostatic test.
RE: Spectacle Bilnds
Here are 2 of several places that rent blinds and flanges.
http://www
http://www.twincoindustrial.com/blinds.html
RE: Spectacle Bilnds
even if cost difference beetween Paddle Blinds Forged and those made from Plate is very variable and not so high as you could expect, basically i'll say: it's most common to specify them form plate.
Otherwise, if your blanks are in CS on services which could cause severe stress corrosion cracking and/or Hydrogen Induced Cracking my advice is to specify forged blanks, in this sense, you have to consider that a blank made from a plate HIC tested is much more expensive than a forged one.
Bye
Giuss