×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*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.

Students Click Here

Jobs

Section I Code Jurisdictional Limits
2

Section I Code Jurisdictional Limits

Section I Code Jurisdictional Limits

(OP)
Hi Everyone,

I was looking into Figure PG-58.3.1 (a) of the ASME code Section I and noticed interesting thing:
Why for surface & continious blowdown from steam drum, chemical feed, vent, soot blowers etc. boiler external piping ends in the first valve, but for drain, feed for integral economizer/superheater two or more boilers, blow-off from water/mud drum it extends to the second valve? Is there any reason for this?

Thank you,
Curtis

RE: Section I Code Jurisdictional Limits

Read PG-58.3.7 in Section I. Two or more boilers with independent sources of steam can present a safety issue with only single isolation, so B31.1 deemed this to be under their technical responsibility. Years ago, before B31.1 (formally ASA Piping Code), the "mother code" was Section I (and still is today) boiler code. When the ASA Piping Committee and standard was developed, there was disagreement as to how piping should be handled. Section I committee members would stay with the boiler proper and boiler external piping would be under the new ASA and eventually B31.1.

RE: Section I Code Jurisdictional Limits

(OP)
Metengr,

Thank you for your response.
How about surface and botom blowdowns? What is rationale behind having only one valve in steam drum/surface (continious) blowdown and two valves in mud drum (intermittent) blow-off?

Thank you,
Curtis

RE: Section I Code Jurisdictional Limits

Curtis2004:
The bottom blowoff has 2 valves since it needs a "root" block valve in case the operative blowoff valve leaks due to seat damage. Without such a backup valve, the drum water level could drain to lo-lo water level without a backup preventive measure. The fluid and junk that is removed thru the bottom blowoff is debris , cut rings ( from rolled tube ends), welding rods, and other things that tend to cut the seat on the operative valve. For this reason these valves need to be wye-pattern globe valves- to allow rod-out of debris and refacing teh seat while it is welded in the line. Refer to B31.1 par 122.1.4, 122.2, 122.1.7.C.

One particular problem is that the boiler dwgs which define the termination points do not always define the blowoff connections, and thus the EPC is unable to meet the B31.1 requirements ( or has an excus) iN the above defined paragraphs. So, if you are the end-user, your spec for the boiler/hrsg shoud require the boiler mfr to define whcih termination points are the blowoff connections. I had seen one case where the blowoff was not defined, and the construction contactor had run flexible pipe from the root valve to a drain pit- when the blowoff was opened,the flex piping failed and flayed about in a deadly manner. This is what was supposed to be avoided by the above paragraphs.

The surface blowdown is sourced from above lo-lo water level, so technically it cannot lead to a lo-lo water level if it leaks.

"Nobody expects the Spanish Inquisition! "

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.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources