Designing a Water / Wastewater Treatment Plant to ASME B31.3 4

[alexcmmi]

Kind of general question as to the design of a water or wastewater treatment plant to B31.3 standards.

Does B31.3 apply to water / wastewater treatment plants? Is it applicable?

How does B31.3 relate to AWWA standards?

I know this is incredibly vague. Just want to see if anyone has any thoughts / comments

 

[stanier]

I have used B31.3 for design of Ro desalination plants as the pressures involved exceed the AWWA and other water industry standarfds.

There is absolutely no reason why ASME B31.3 cannot be used for the water industry. the design, fabrication inspection and testing will produce a piping facility you can depend upon. Certainly any austenitic, duplex or super duplex piping will be well covered.

It can also be used for GRP with a material guide such as ISO 14692 rather than the out of date BS 7159 or the water industry AWWA M45.

Many water and waste water industry plants have dangerous chemicals and use of B31.3 is suitable.

 

[KenA]

In cases where the water / wastewater plant is an intengral part of a larger hydrocarbon complex then I believe that it is fairly common to continue the use of B31.3 across the whole plant, including the water areas. I'm guessing that this is generally done to simplify / standardise the piping design and materials. But I guess that it must add some cost.

 

[alexcmmi]

Thanks guys. KenA, that is exactly the situation we have here, the water treatment plant is part of a larger facility that is being designed to B31.3. It does indeed add cost and time.

All chemical feed systems to the water treatment process will be designed to B31.3. But this is small diameter (less than 2"), low pressure, low temp piping. No thermal movements expected. Short pipe runs and pretty straightforward piping system.

The 'problem' becomes designing the 20" and greater, flanged DI to B31.3. That is just not common / done at municipal water and wastewater treatment plants for the most part - for several reasons. The burden of providing pipe supports is often left to the contractor in those types of municipal design-bid-build projects, and is often covered somewhat vaguely in an interior process piping specification (a spec may reference MSS standards for supports).

These are pretty straight runs, the building is ~100' x 100'. Pipe is layed out in AutoCAD, not in AutoPipe, ceasar or these other analysis systems.

Is there any way to provide a simple, cose effective B31.3 analysis on this pipe that does not significantly impact schedule?

 

[tnboy82]

I do not know of any AWWA standard that is directly related to B31.3. That said, I am also not familiar with B31.3. I would suggest contacting the Ductile Iron Pipe Research Association (

http://www.dipra.org)

and see if any correlation exists between the ANSI B31.3 and applicable AWWA/ANSI/ASTM standards for ductile iron pipe may be substituted in lieu of B31.3. If so, then DIPRA has a set of computer programs (which are free) for the design of ductile iron pipe which may be useful.

 

[bimr]

What you should be referencing is an in-house piping standard.

Guidance supplementing piping standards is necessary because the various codes provide no explicit rules for functional design, material compatibility with fluid and environment (erosion/corrosion protection, radiation effects, etc.), layout, serviceability, steam tracing, grounding, valve and component selections, design of pipe supports, material traceability, gasket selection, as-built tolerances, insulation, cleaning for special process, etc.

For certain services some options available through piping codes must be excluded, made more stringent, or supplemented by the designer.

Larger CPI and HPI corporations have in-house piping standards that guide the design of piping systems.

If you do not have access to any corporate standards, I would build on the standards that were developed by other firms. It would be wise to read through a few of these standards for design inputs.

Have are a couple of references:

http://engstandards.lanl.gov/engrman/6mech/pdfs/D20-AppA-ASME_B31.3-r1a.pdf

US Army Engineering and Design - Liquid Process Piping

http://www.usace.army.mil/publications/eng-manuals/em1110-1-4008/toc.htm

 

[stanier]

Change the DI piping to spiral wound stainless steel and this falls right into the B31.3 design code. You will also find it cost effective against DI.

 

[rconner]

Owners of water and wastewater plants at least in municipalities with long history have for many decades had access to, and in many cases at least some direct experience with, many different choices for piping materials, including all those mentioned on this thread. I believe (based on looking at a lot of plans and specifications for many decades) that a major if not THE major choice at least in most fluid handling lines (and particularly for the very largest/in many cases oldest municipal plants/users with longest experience) is ductile iron piping. I suspect there is a whole lot that has been considered in this useage.

While of course Engineers certainly have a right (and daresay responsibility) to specify/design whatever piping system in their experience/opinion/analyses will do the best job, and not saying whatever pipe material will not work for any particular treatment application, different piping materials are not equal in many respects including successful performance history. Care should be applied and maybe particularly in making changes to known and long-term successful practice. Perceptions and whatever code or piping standard one thinks should be applied do not necessarily change these realities.

In this regard, and while stainless steel has great utility in many applications and "stainless" is a great marketing term, any folks who have been around the piping/tubing industry for any length of time know that particularly fabricated stainless steel is in practice/rigorous technical examination not necessarily "stainless" (in the literal meaning of the term), nor is it necessarily in the quite thin welded schedules often promoted devoid of some even more serious corrosion issues in long-term piping applications (and maybe even in some basic treatment applications where more common, alleged "legacy" piping materials with contemporary cement etc. linings etc. have done pretty well).


"Do not hold everything gold that shines like gold".

12th century French theologian Alain de Lille

 

[scoho83]

What I am confused about is the "need" to do stress analysis on a pipe he said will not see any thermal fluctuations. As an owner, (or a design firm making recommendations to owners) you can set-up "practices" in your specs as to when stress analysis is required. If you know you have no "real" stresses other than loading, (which you have span rules to accomodate) you shouldn't need to run Ceasar. (If you have good piping design with flexibility allowed).

 

[cheute79]

Just stumbled upon this thread, and maybe a bit late to provide any value, but stress analysis for water and WW is typically limited to the issue of "warm", empty pipe heated in the sun, or "cold" empty pipe exposed to <0°F pipe, and then filled, and to pump (flow/pressure) cycles, that are usually pretty low (relative to some process streams). The water is seldom outside a range of 50-90°F, and so thermal stresses during operation are minimal.

Materials for municiple WW are as rconner has discussed. As a process Chem E, I do an increasing amount of WW systems design because they are for industrial systems, and the issues are not presented in typical sanitary eng'g handbooks, nor well understood by suppliers. You need to consider what the stream is composed of, and where it is going. Some industrial is thoroughly treated and put back into the process. So, if you are treating through RO or even DI to return to the process, at some point ductile iron is not appropriate, and stainless may be the wrong material. CPVC or ABS might be the way to go.

 

[stanier]

Plenty of 316L austenitic stainles steel used in water and watewater plants. Refer

http://www.nidi.org

for some very good technical papers on the subject.

With tight programs it is certainly more flexible to use than flanged ductile iron.

The agian many lants use ABS, PP, PVC GRP these days as they are certainly cost effective against the legacy materials. For large sizes PE or epoxy coated steel has proved to be a useful material.

 

[rconner]

while there is no doubt the utility of the material in some fields and applications, and it is also apparently true as stanier states that stainless steel has seen some increasing treatment plant use, particularly in last few years and e.g. and in some European areas etc. I noticed recently however that after generally only a few years of use some issues have developed in plants, and even with some 316L etc., and it is e.g. the subject of a Danish research program that was summarized at

http://www.force.dk/NR/rdonlyres/C009DC48-B075-4950-BDF1-0ADA33D51DD8/0/060704_03563.pdf

that makes an interesting read (I don't know if this paper and other third-party papers I have seen is on the site stanier refers to).

 

[stanier]

Thanks rconner for the link.

Many plants in Australia & SE Asia have been using spiral wound stainless steel for over twenty years. The success comes from doing properly.

engineering the thin wall stainless steel so that there are reinforcing pads at branches. Doubling plates to prevent local buckling stresses at pipe supports. That is using qualified weld procedures, qualified welders , pickling and passivation.

Hence if you are gong to use ss in these plants ASME b31.3 is a good choice to ensure that the design, fabrication, testing, installation and operation will succeed.

Others will claim that this is level of engineeering is unnecessary for ductile iron piping. Years of seeing design by cataogue for DI is testimony to the fact that it can be done. Hence ss will cost more in engineering but generally less in supply/erect than ductile iron. DI is generally remanufactured from scrap ferrous products. The price vaaries with supply. Ss depends on the price of nickel, which has just nose dived. It depends on where you are in the world as to the overall cost.

Myself I prefer ss as I have control over the engineering, particulalry in this litigous society.

 

[stanier]

rconner,

Having read the link the conclusions for successful use of ss in treatment plants are ;

1)Do not use grad 304ss
2)When using 316 or 316L use qualified weld preps and welders,
3)Pickle and passivate the welds

Our own conclusions precisely. ASME B31.3 is the way to go.