Fitness for Service, piping 5

[Rjeffery]

I am trying to locate references that will help me determine if piping containing steam (for heating) has lost sufficient wall thickness to require replacement. The B31.1 has a section on fitness for service but it is limited to the boiler and feedwater systems... Google is of little use.

 

[metengr]

Regardless, I would still use the applicable section in B31.1.

 

[TGS4]

You could try ASME FFS-1/API-579.

 

[TBP]

What kind of heating system? How much wall thickness loss have you detected? It's not very often that steam lines suffer much (if any) reduction in wall thickness.

 

[metengr]

It's not very often that steam lines suffer much (if any) reduction in wall thickness.

What????? Here is a tip; I have seen local corrosion pitting attack on the ID surface in boiler external piping caused by oxygenated, stagnant condensate (poor drainage).

 

[TBP]

metengr - The way I read the question posed by Rjeffery he's asking about distribution piping for on a steam heating system as opposed to boiler external piping.

Thanks for the "tip".

Anyway, my questions remain:

1/ What kind of heating system?

2/ How much wall thickness has actually been lost?

 

[Rjeffery]

TBP:

1/ large capacity municipal office heating. (not sure how to answer other than that) Pressure and temp are over dist. piping definition.

2/ % loss is hard to calculate as piping may be XS or STD vs Sched. ie "old"

 

[MJCronin]

Try API-570

ANSI/API 570 Piping Inspection Code: Inspection, Repair, Alteration, and Rerating of In-Service Piping Systems

http://www.techstreet.com/cgi-bin/detail?product_id=4158

-MJC

 

[TBP]

The designations of "standard" and "extra-strong" (or (extra-heavy") have been around for probably 100 years or more. The Sch 40 designation matches standard wall thickness up to 10" pipe, and sch 80 matches XS (or XH) up to 8". It would be unusual (as in serious overkill) to see sch 80/XS steam lines in an application like yours. The condensate lines may well be sch 80/XS for corrosion allowance.

In any event, in a system like yours, I doubt very much that the steam lines have lost any measurable wall thickness. The condensate system is FAR more apt to have suffered the effects of corrosion. But having said that, I've seen photographs of 100 year old wrought iron condensate piping that had lost less than 10% of its' original wall thickness. That particular system is very much the exception, though.

 

[gerhardl]

Knowing nothing about, and having not read mentioned standards, I would anyway like to add some thoughts:

Even if standards are explicit on procedure, you will anyway have an overlaying risk evaluation to do, deciding or presume something about not only the present standard of the pipeline, but also the expected 'safe' rest lifetime.

The consequences and cost if bursting, and the chances of a failure someplace on an extra weakened spot not found by one or several check methodes have also to be considered.

The previous history and mode of use and maintenance, general condition, quality of layout, correctly mounted and inclined / fastened, the quality of steam,the steam pressure, the maintenance or existence of steamtraps will tell something about extra risk of waterhammer or condensate resting in pipeline and also something about extra risk and spot risk of wear and corrosion in the past.

Likewise will the same points for the future prolong or shorten the expected future lifetime.

 

[LSThill]

Rjeffery (Civil/Environme)

Inspection Planning, PCC-3,

L S THILL

 

[jte]

Leonard-

I don't think PCC-3 has been published yet… when it does, it'll look remarkably similar to the corresponding API publication (581?).

jt

 

[LSThill]

jte (Mechanical) I agree PCC-3 is simlar to API-581

Comment Deadline: September 25, 2007
ASME (American Society of Mechanical Engineers)
New Standards
BSR/ASME PCC-3-200x, Inspection Planning Using Risk Based
Methods (new standard)

Provides information on using risk analysis to develop and plan an effective inspection strategy. Inspection planning is a systematic process that begins with identification of facilities or equipment and culminates in an inspection plan. Both the probability of failure and the consequence of failure should be evaluated by considering all credible
damage mechanisms that could be expected to affect the facilities or equipment. In addition, failure scenarios based on each credible damage mechanism should be developed and considered

Obtain an electronic copy from:

http://cstools.asme.org/publicreview

Order from: Mayra Santiago, ASME; ANSlBOX@asme.org
Send comments (with copy to BSR) to: Steven Rossi, ASME;
rossis@asme.org

L S THill