"Unfired Steam Boiler" vs. "Power Boiler"

[chbake]

The state of Tennessee desires to classify our Waste Heat Boilers as "Power Boilers". The subject boilers cools process gas which consists of SO2 for the purpose of making 450# steam. As an organization, we wish to challenge this classification, and categorize the subject boilers as "Unfired Steam Boilers". I am looking for a reference, book, web site that elaborates on the design specifics, requirements, provides examples and/or technical definition of an "Unfired Steam Boiler". With regards to classification, I have researched ASME Section I and VIII code, and the definitions don't appear to be very detailed. There seems to be a little subjectivity in the interpretation of “Power Boiler” vs. “Unfired Steam Boiler”. We would like to eliminate some of this ambiguity by locating as much information as possible.

 

[athomas236]

chbake,

As UK consultants we have in the past been offered unfired waste heat boilers designed in accordance with both ASME I and ASME VIII and have accepted both. This is because in ASME VIII there is a clause that refers to compliance with certain clauses of ASME I that refer to matters like drum level indication etc. As a consequence, I cannot see any advantage in classifying unfired boilers as either ASME VIII or ASME I.

athomas236

 

[spector]

As an organization, you should make an effort to comply with your jurisdictional laws. What you are seeking is a way to exclude your boilers from certain requirements that are in place to help guarantee safety. Consider ASME I and the NBIC as a minimum standard. But feel free to set one yet higher.

How does your boiler/machinery insurance company address the matter?

 

[69691]

Individual states and in some cases, jurisdictions within a state can set their own rules. Unfortunately, there are no standards/codes that everyone uses. The ASME Codes are there as a guide and a state can use them in there entirety or just a portion of them or not at all if they choose. In the state of Massachusetts for example, the Department of Public Safety dictates thats all unfired HRSG's will be ASME Section 1 Code constructed. Not everyone agrees, especially the boiler manufacturer's, but that's the law.

 

[spector]

Charles Baker,

You can believe the Chief Boiler Inspector of Tenn and most of his deputies frequent this site.

Perhaps you should discuss it with him privately.

 

[deanc]

Strongly suggest you follow "spector's" advice.

 

[jehar]

Hi chbake,
I spent many years(over 30) designing and manufacturing Heat Recovery Boilers, and the rule we always followed was that if the hot gasses are the products of combustion, then it is a Section I boiler.
It doesn't matter if the combustion takes place a few feet from the tubes, or hundreds of feet from the tubes.
Thanks,
Jack Hardie

 

[athomas236]

69691,

Thanks for the information about some States policy to ASME Section I. In the international market we tend to use the whole of ASME without any deletions or additions. Your information makes me wonder if this is a completely satisfactory policy.

Regards,
athomas236

 

[spector]

Please excuse my short response, but I'm a tired old boiler inspector. Tired of hearing the same old attempts to prevent/circumvent/evade compliance......Boiler laws are adopted and enforced for just one reason-To keep you in business...Some will say 'safety', but the bottom line is $$$. It cost big money to bury your dead-To satisfy their lawyers-To rebuild your plant....And to try to catch up with lost business.

The ASME and NBIC codes came about when this country was experiencing castastrophic losses from boiler explosions. Nearly every page of those codes are written in blood...And the boiler owner, if he escaped the carnage, survived to suffer tremendous business losses and additional liability from dead/injured survivors and their families.

Yet everyday of my inspection history, I had to watch for 'organizations' trying to destroy themselves by curcumventing the law in an attempt to keep steaming.

Sorry Charlie, boiler inspection is a fact of life. And the sooner you embrace it, the sooner you welcome it, the sooner you plan it into your other shutdown maintenance requirements, the sooner you will benifit from it.

If all it is and has been to you is trouble, then take it upon yourself to make the event productive. Discoveries made during inspection can be worth their weight in $$$. Inspection can reveal how effective your maintenance and chemical treatment plans are. Inspection can help you plan shutdowns rather than react to them.

The old saying goes, "You get what you inspect, not what you expect."

I love those old sayings, I hate they must forever be repeated.

 

[chbake]

Thanks for all of your insight. We reviewed our application with the local jurisdiction, and apparently, ASME section I or section VIII is applicable. It's a design choice. In our case, the boilers were designed to section I to achieve improved mechanical integrity. However, based on applicable state code, the boilers are unfired steam boilers requiring a 2 year inspection frequency.

 

[EngineerBSME]

Thanks, Spector(Mechanical), for your response.
As professionals, we are here to protect the public, not to please the boss and temporarily line our pockets, or matter of factly, feed our families on the blood of someone elses.

Suppose the local hospital decided, rather than close their doors, cut cost by sharing used needles? Please close the doors.

 

[Chris2743]

I'm glad you saw the light and then decided to accept the jurisdictions decision...I've been in the fabrication business for ASME pressure vessels for 30 years and initially fought it tooth and nail, but eventually over time I began to see the wisdom of designing and building these things in accordance with the code, it really is designed rules and regulations written in the blood of people before us, pay attention to what it has to say

 

[spector]

You're welcome Sir,

I'm sitting directly under a DFT containing 2000 gallons of water at 227 F, 5 PSI....I'm scared of it. It hasn't undergone an internal inspection since it was placed in service back in 1986. The reason? It's not "required" in this state.

I again today waved additional evidence of catastrophic DFT failures at my boss. He finally agreed that it must be inspected.

Am I an alarmist? I don't think so. I lived for many years inside a pressure vessel. Outside that shell was all the water in the world pressing in on me at 700 PSI. I never recall being scared then, but I am now.

In the early 80's, industry experienced several DFT failures. People died. Once the world woke up to the danger, they began to inspect their DFT's. Over half of the vessels inspected revealed severe cracking. All were either repaired or condemned. Well, not all....I'm sitting under one that people neglected to inspect.

 

[GenB]

I have discusse dthe topic with many boiler inspectors/supervisors and chiefs as well and all agree
on the subject of the unfired steam boilers:
they are power boilers!.-
It is there in the preamble/first pages of the sec. I of the ASME Code, it just hard to find and read.
ER

 

[davefitz]

For a good text on this subject, read "Power Boilers" by Marty Bernstein and Lloyd Yoder, p9-10, ASME press 1998

Usually if the heat is from the products of combustion, it is a power boiler, but not always. Somes HRSG's may at times be considered unfired .

A power boiler requries an annual inspection, . An unfied boiler fo section VIII must meet more stringent rules for vessels, such as ad'l X-ray, PWHT, and impact testing. And of course section VIII recognizes fatigue damage while section I is blissfully silent on this issue.

 

[bvi]

Boilers using waste process heat can certainly be built to Section VIII, Division 1 and the rules of that code result in safe construction. Look at the scope, of Section VIII, para. U-1(g). ...Unfired steam boilers as defined in Section I shall be constructed in accordance with the rules of Section I or this Division... ...The following pressure vessels in which steam is generated shall be constructed in accordance with the rules of this division.........U-1(g)(2) vessels in which steam is generated by the use of heat resulting from operation of a processing system containing a number of pressure vessels.........

In this particular case, the vessel was already constructed to the rules of Power Boilers (Section I) so the jurisdiction was quite correct in requiring it to be treated as a Section I boiler. But Section VIII is a perfectly legitimate choice for original construction (which the jurisdition understood, per the final comment from chbake). That being said, you still need to comply with the requirements of the local jurisdiction.