ASME Code Vessel required for Multimedia Water Filter ? 5

[BryceV]

We are looking to add a large multimedia filter to filter the city water coming into our plant (we have issues with high SDI into our RO system).

This filter is a large horizontal vessel (8' dia. x 40' long). The vendor sells these as non-coded vessels, but for an adder can build per code and get them a NB registration. The vendor says they use the same materials and basic methods either way, it's just the inspection and paperwork that makes it coded.

My gut says for water(non-compressible) fluid, that there really isn't a safety concern here as you would see with a compressed air tank which we also have and are ASME stamped/coded, etc.

Our plant is in Alabama which is a code state, but there is an exemption from ASME registration for all manufacturers. I'm trying to get an answer out of FM Global on what they require, but have nothing definitive. Does anyone have any guidance, specs., thoughts on this ?

Thanks,
Bryce.

 

[metengr]

Yes. Contact the Jurisdiction in Alabama (Safety Division) that regulates boiler and pressure vessels and review their rules for unfired pressure vessel exemptions. FM Global cannot require anything, they must abide by local rules regarding unfired pressure vessels. If there are no rules, you can build with or without an ASME U stamp.

 

[jte]

The vendor says they use the same materials and basic methods either way, it's just the inspection and paperwork that makes it coded.

Buy the vessel without the stamp. You'll save 5% up front and will probably be promoted or transferred to a position where it won't be your problem when the problems come up. Don't forget, the fabricator needs to build some non-Code vessels so that their apprentice welders will have something to practice on before they get Code qualified. Brittle fracture due to a hard weld might not happen...

jt

 

[vpl]

I'm pretty sure jte is joking...

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[vesselfab]

Does your plants liability umbrella insurance require code?

if this will have city water pressure 40-50 psig, I know i would want it stamped.

 

[BryceV]

Thanks Patricia. I noticed the sarcasm pooling around JT's e-mail...

Not trying to shortcut anything, want to do what's right, but don't want to overkill it. This vendor has sold several non-coded vessels in the same application... so either all those companies are stupid/crazy/ignorant, or there's something I'm missing.

Safe bet would be to get it stamped I supposse, but it's more like 20% adder than 5%, so it gives me reason to pause and think a bit.

I may just contact the Safety Division of AL per metengr's post, but as I read the code, there is an exemption for all manufacturers... which is a pretty wide swathe of people. If it were really that dangerous, why the huge exemption ?

 

[metengr]

BryceV;
You have no option regarding contacting the Jurisdiction because if they regulate unfired pressure vessels you need an Operating Certificate or you do NOT operate the vessel. Yes, there is typically an exemption for water filled vessels that do not heat the water directly or indirectly. This service is indeed safer, and this is the basis for the exemption.

 

[sbush]

We build vessels for water treatment like you described. In 1989 the Scope Section (U-1) of the ASME Section VIII, Div. 1 was amended. As a result, vessels used for cold water and low pressure, that do not contain compressible gases (like air), do not fall within the scope of the ASME code for un-fired pressure vessels. This does not mean that you cannot have them certified and stamped. Almost every state that I have check with recognizes the 1989 addendum and the change in the Scope U-1.

We build both ASME certified and standard (non-code) vessels, and all of our welders are ASME certified. The main differences for us, is the non-code vessels can use standard F&D heads (i.e., more shallow, not as tall) and the non-code thickness calculations use 100 percent joint efficiencies which usually results in somewhat thinner material. We don't hydrostatically test non-code vessels either. For us, the advantage to using non-code vessels is about 2 weeks off the completion time.

S. Bush

http://www.water-eg.com

 

[BryceV]

Thanks S.Bush ! Exactly what I was looking for... I'll have to try and get a copy of the code to review that section (I probably should have started with that).

Just odd that most folks can't explain this, especially those folks that are making these pressurized water filters.

 

[jte]

sbush-

A good response and interesting to hear from one who is in the business of fabricating these types of vessels. As you mentioned, VIII-1 U-1(c)(2)(f) provides the water storage exemption, though, as you also stated, the vessel may be brought into the scope of the code at the request of the owner/user.

However, it is seems that you are not the fabricator which Bryce is considering using, though perhaps I misread the original post. Apparently the fabricator has indicated that he uses "the same materials and basic methods either way, it's just the inspection and paperwork that makes it coded." I read that to mean the same type of head and the same thickness of steel and the same testing regime.

As you point out, you offer similar but clearly different vessels to your customers depending on whether they request the stamp or not. A ~15% reduction in thickness (I'm presuming your stamped vessels get spot RT) might be considered significantly different. Shallower heads which may be more prone to buckling at the knuckles under internal pressure might be considered significantly different. Not hydrotesting the vessels means not only that, well, they aren't tested, but that the stress redistribution/relief benefit which hydrotesting provides (e.g. at nozzle-shell intersections) is not present. Are the weld procedures the same (even if Code qualified welders are used)?

I guess the question for Bryce is two-fold: First, does he have a legal or contractual (jurisdiction/insurance/other) requirement to use a stamped vessel even if it is out of scope of VIII-1? Second, does the cost benefit (both intitial and inspection/maintenance/repair including pressure relief device) justify the similar, but arguably lower quality, vessel?

I've often made the argument that if something can be excempted from the Code, there is a significant maintenance benefit from doing so. In addition, the "courtesy pressure relief device" can be deleted, again deleting future routine tracking and maintenance. But in this case, with a vessel of this size, I'd favor getting the U stamp. I won't say that it is common, but people have been killed when a vessel full of water failed catastrophically and they were swept off the platform to their deaths by the flood. There's about 60,000# of water in this particular vessel.

jt

 

[sbush]

Jt,

In the beginning (a Garden of Eden metaphor), there was only black and white. But, then there was gray.

I think this gray area could be part of the reason for the amendment to the U-1 Scope.

For water treatment vessel manufacturers, like myself, the ASME code is a great way to ensure that everyone is bidding to the same design specs in a competitive situation. But, in the normal water treatment plant situation, catastrophic vessel failure is extremely rare and possibly non-existent. In thiry years, I haven't heard or seen anything worse that a few pinhole leaks, and I have seen non-code vessels pressurized to far in excess of their design and to the point of deformity.

Black, white or gray: it is solely the responsibility of the buyer to make sure that he is buying the right vessel from the right source and installing and using it properly.

S. Bush

http://www.water-eg.com

 

[BryceV]

Jte, thanks for the more thoughtful post this time, I guess your first post was meant to be sarcastic/funny, but it was thoroughly unhelpful.

Sbush is dead on... it's a very grey thing... not obvious on what to do. I'm all about being safe, but I'm not about throwing good money after bad just to give the appearance of being safe. And I want a grounded position, not just pay a chunk of change to "make it safe", when there's no basis for doing so.

Anyway, I appreciate all the discussion, it's very helpful to talk this through with some interested and knowledgable parties.

 

[sbush]

Bryce,

Since your vessel supplier has already indicated that their standard vessel is equivalent to an ASME design, sans inspections and stamp, why not request that they furnish copies of the backup calculations, material certs, heat numbers, and request a photograph or video of the hydro test. We have even had requests for a pipe tap (usually 1/2" NPT) with a removable plug for checking the thickness of the heads and shell. Also request a copy of their current National Board Certification. This won't necessarily guarantee that your vessel will be welded by a certified welder, but it will indicate that they have them on staff and that the manufacturing facility meets all of the criteria required by the ASME and National Board.

As with any pressure vessel, code or non-code, make sure that a properly designed/sized automatic air release valve and pressure relief valve is provided and installed with each vessel. And consider any potential for hydraulic surge from the system (this has more to do with internal piping issues within the vessel).

In this particular case, the ASME code requirements would build-in an independent third party inspection system. However, if you are a savy buyer (and you seem to be), you can have your cake and eat it too. Just check out the suggestions made by the other posters above, weigh the options, consider the risks; then make an informed decission (piece of cake!).

S. Bush

http://www.water-eg.com

 

[HEC]

Bryce,
The service you mention, as a filter, will it be hydraulically solid during the entire operating cycle. I have operated media filters in the past where an air scour was required as part of the backwash. Although usually hydraulic solid and therefore low risk most of the time they needed to be registered vessels. Additionally there may be air come in with the water supply. In any case is there a guarantee that the vessel will be hydraulic solid all the time. If not I would stay with the registered vessel.

Additionally I agree with jt, what would you do with 27m3 of water that will enter your plant suddenly if the vessel fails!


Mark Hutton

 

[sbush]

Mark,

In a properly designed filter with air scour feature, the vessel is removed from service, then de-pressurized prior to introducing air. Upon completion of air scour, the vessel is completely refilled with water prior to returning to pressurized service. If this was not the case with your particular filter, then there should have been an automatic air release valve to completely evacuate air at all times while the vessel is in service.

Pressure filters will not operate properly with air present. This is true whether the ASME stamp is affixed or not.

There seems to be a perception by some that the ASME label will automatically compensate for or catch and eliminate any deficiencies in design or manufacturing. This simply isn't so.

You guys paint a pretty disturbing picture of Bryce under ten feet of water and wishing he'd spec'd the ASME label. My guess is, however, Bryce has got one or more floor drains with ample capacity to discharge whatever erupts from this vessel...ASME label or not.

I don't mean to be contrary. I'm just trying to keep things real.


S. Bush

http://www.water-eg.com

 

[BryceV]

I have my scuba gear and flippers... bring on the filter vessel !!! Actually, this filter is located outdoors in a somewhat remote location... so in the very unlikely event it lets loose I'm not worried about the water. Bigger concern would be any injuries from the immediate failure. But as discussed this would be a very very small possibility. (impossibility ?)

Mark, we're just filtering city water so no chemical filter aids are planned (and hopefully never needed), so no air scour incorporated.

Thanks Sbush for the additional comments ! All are excellent points and I will make sure I account for those items. And yes, this unit has an automatic air release. Sadly I was thrown into this rather late, otherwise I'd love to give you guys a chance to quote... at this point I need to get the order out, the project waits for no man.

 

[JStephen]

Here in Texas, I think these filters are normally built with an ASME stamp.

The way Section VIII is written, I believe hydropneumatic tanks are actually exempt (they can be built up to 30,000 gallons or so), but the state requires them to be ASME stamped as well (old ones were grandfathered, however). This is not the state pressure-vessel regulators requiring it, but the state waterworks regulators.

 

[BryceV]

I got my hands on a copy fo the 1989 edition (I don't have a more recent copy) of the Section VIII, Div. 1 B&PV code per SBush's suggestion.

The U-1 Scope section reads:

(c) The following classes of vessels are not considered to be within the scope of this Division:
(6) a vessel for containing water under pressure, including those containing air, the compression of which serves only as a cushion, when none of the following limitations are exceeded:
(a) a design pressure of 300 psi
(b) a design temperature of 210°F

So that's what I was looking for as far as an exemption from the B&PV code...

But JStephen makes a point about local/state or even water works requirements... the trick with calling anyone is if I were to ask "Does this need to be a coded vessel?", I'm sure the knee jerk answer will always be "yes". Sigh... I'd rather see something in writing, but at least I know I'm clear as far as the ASME standard is concerned.

 

[sbush]

Most of the enforcement officials around the country that I've talked with have addressed this question many times and are aware of the U-1 "Scope" requirements. They will probably send you a copy of their State's regs too.

In Alabama, contact: Administrator, OSHA, 600 Administrative Bldg. 64, North Union Street, Montgomery, AL 36130.

My copy of the Uniform Boiler and Pressure Vessel Laws Society, Inc. does not list and cities or counties with special enforcment officials, but you should check with your city or county to verify this yourself.

S. Bush

http://www.water-eg.com

 

[JoeTank]

BryceV,
Notwithstanding all of the fine advice you have received thus far, I'd like to offer my two cents. As a former employee of a pressure vessel shop I can tell you with great confidence that the guys on the shop floor do not trest the non-Ccode vessels with as much respect as the ASME Code stamp vessels. While the designers consider them as essentially equivalent, that respect does not translate fully to the shop floor, the QC dept, etc. I have been inspecting, evaluating and re-rating vessels for over twenty years now and I can confirm the results of buying non-Code vessels... it's spotty at best. Some look just like an ASME-Coded stamped vessel, BUT some don't. I'd spend the extra for an ASME Code stamped vessel.

Joe Tank