Pressure - temperature rating for piping components 1

[Drexl]

Hi,

I'm designing a piping system for steam, say with
Design pressure 12 bar(g)
Design temperature 200 degC
Material P235GH

Picking flanges according to EN 1092 is very easy. I just look at the one PN-class at the time until i find one that satisfies my pressure/temperature combination.

But what about other piping parts like straight pipe, bend, reducer, T-piece etc. These i have to calculate case by case according to EN 13480. This is very time consuming.

Where can i find precalcuated pipe classes including all the above components with given pressure/temperature diagrams, as the case with the flanges??

best regards

 

[jte]

You can find your answer from your friendly local mechanical engineer. We do more than just look up things in tables. Really.

jt

 

[Drexl]

Actually I have asked around and all I hear is, well it's too many factors like corrosion allowance, welding factor, manufacturing tolerance. Because of this we have to calculate the same parts over and over for new projects.

At the same time I have found precalculated pipe classes for some PN/materials in local standards, so the above reasons are not true. Reinventing the wheel is not a good thing.

 

[jte]

Exactly the reason I feel that we shouldn't be redesigning the process for steam systems every time we develop a new plant which uses steam. Can't we just pull the process requirements from a table or just copy the last plant we did without regard to say atmospheric conditions, plant elevations (one flat, the next built on a slope), feedwater quality...We shouldn't be reinventing the wheel every time we need a new plant built!

jt

 

[BigInch]

Ya, by now everything should just come ready for a simple 3D printing.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[JohnGP]

Ah, it's good to start the day with a bit of a chuckle.

 

[Drexl]

Ok, now i have found the following precalculated pipe classes in a standard.

P235-PN10
P235-PN16
P235-PN25

1.4436-PN10
1.4436-PN16
1.4436-PN25
1.4436-PN40

Each pipe class has a given p/T ratings from 0-400 degC and include pipe components (spool,bend, reducers,Tee,flanges,caps..) in sizes DN20-DN1000. I only check what my system pressure and temperature is once, select pipe class and start picking components. Easy. This should cover > 70% of my need.

 

[Drexl]

Regarding your comments. Once you have designed a plant, you definately try to sell the plant as standardized as possible to the next customer, all changes will cost a lot of time and money. But you already know this, and know that there is a big difference between a few standard piping components and a power plant.

 

[jte]

Whatever. Glad I don't live in Finland anymore.

jt

 

[europipe]

Where are the good old pipespecs?

 

[Drexl]

europipe,

When I created my pipe spec for the example above, I just looked in the standard, picked my pipe class P235-PN25 and copy pasted all components into the pipe spec in my 3d-tool.

I added some valves specific to the actual system and now i have a ready to use pipe spec (i hope). How do you usually create your pipe specs? Would be good to know as I only have my own example to compare with and really would like to understand this better.

jte, good for you, but please give some examples or explain your opinion instead of just mocking the thread.

 

[pennpiper]

Drexl,
Your "Tag" lists you as "Chemical" If this is correct then are you a Process Engineer working for an Engineering and Design company or are you the owner?

If you are the owner of the company of course you can do anything you want.

If you are the Process Engineer then you should NOT be specifying piping materials or developing Piping Material Specifications.

Also, you are wrong that once you develop Pipe Specs for one job all you need to do is copy them to the next job. There is no such thing as a duplicate job.

Please leave piping to the pipers.

 

[IRstuff]

OMG, you figured out the secret; there is no need to have any piping designers anywhere! They are completely superfluous...

In the best case, your "design" might work OK, or you'll be at another company when your "design" fails and causes a massive accident.

Just because you can find all the parts at the local auto parts store catalog doesn't mean you can, or should, design your own car.



TTFN

FAQ731-376

 

[Drexl]

pennpiper, you are correct that this is not the process engineers problem or responsibility. This said, I still need to understand it. I'm not saying that pipe specs always can be copied, but can you give some good examples when not? Different standard, availability for components/materials can vary in different parts of the world..

IRstuff, come on. Pipe designers do a lot more than calculate pipe thickness. You have to route pipes, make isometrics, perform stress calculations etc. Maybe you have other examples also..

 

[Ron]

Drexl...I get the impression that you think engineering is looking up info in tables and using standardized "crap" to develop your judgment. Not so!!

Those "factors" such "like corrosion allowance, welding factor, manufacturing tolerance" actually have relevance to design and successful implementation/performance. To ignore those is irresponsible.

GET A MECHANICAL ENGINEER TO HELP WITH THIS!

 

[Drexl]

Ok, never mind. I see that I will not get any advice here.

 

[IRstuff]

There was plenty advice given, just not the kind you wanted to hear. So, "not get any advice here" is a suspect statement, and raises all sorts of questions.

I think that you need to be asking yourself why you are rejecting the advice from several senior, and experienced,
engineers.

TTFN

FAQ731-376

 

[pennpiper]

From another question at another time.

Piping Specifications
The question:
How to make pipe spec. & what is basic need/data for that?

My answer:
First, let’s see if we can clarify which “pipe spec” you are talking about. You must realize that the term “pipe spec” can be both general and specific at the same time.
Here is most U. S. Companies there might be as many as thirty Specifications that cover piping related issues. There may be a “pipe spec” for:
• Piping Specification for Plant Layout and Design
• Piping Specification for Shop Fabrication
• Piping Specification for Field Fabrication and Installation
• Piping Specification for Hydrotesting of systems
• Piping Specification for Hot Insulation
• Piping Specification for Cold Insulation
• Piping Specification for Pre-Engineered Pipe Supports
• Piping Specification for Engineered Spring Supports
• Piping Specification for Line Class Material
• Piping Specification for Valve Purchasing

And the list goes on and on.
This is a partial list of some of the specific “pipe specs” that are found on most projects. Included in this list is one that I think you are asking about.

I think you are asking about “Piping Specification for Line Class Material” or it may be called “Piping Line Class Material Specification” or it may have some other combination of words that mean the same thing. But it is a very specific “pipe spec” out of a very big family of piping specifications.

Now to your question as it relates to “this” pipe spec.
How to make pipe spec?

"Piping Material Line Class Specification"

This document would have a cover sheet and a written section which would include the following:
- Document Title
- Document Control Number
- Table of Contents
- Statement of Purpose and or Function
- General Notes
- A listing of all the Codes that apply to the material included here-in
- A list of all the Line Classes with basic data such as Commodity, Material, Flange Rating, etc.
- Each of the individual Line Class sheets
- The common vent, drain, and other misc. connection details
- Branch Connection Tables (one or more as required)
- Name of Originator (Responsible person), Date created
- Name and date of checker
- Table of Approval for Issue, (Piping Department, Project, Client)
- Table of Issue History listing Revision, date, what was revised, by who, approval sign-off

All of this would then be issued as a single document.

The second part of your question
What is basic need/data for that?

Data Requirements
There are two sides to this question. There is the up front data requirements needed to produce the Line Class Specification. Then there is the output data or, what does each line class need to include?

So, first what is required to start? You need, as a minimum the following information:
• A list of every commodity that will be a part of the project. This means the feed, all products, all waste streams, all utilities and all additives.
• For each commodity you need the complete chemistry including Toxic classifications and reactions to changes in temperature. Here in the U.S.A. we have a document called a “MSDS” (Material Safety Data Sheet). These have all the chemical, toxic, medical recovery and other data about a chemical be it a gas, a liquid, a powder or a solid. If these are available in your country then get a copy for your records of the MSDS for each commodity.
• For each commodity you need the maximum sustained operating pressure and temperature.
• For each you need to know of any short term or upset condition that may cause an increase or decrease in pressure or temperature.
• For each commodity you need to determine the corrosion rate for different (common or special) pipe materials.
• For each commodity you need to know the projected maximum and minimum pipe size expected for the project.
• You need to know the location of the jobsite and the full twelve month weather/temperature profile.

When you have collected all this information then you need to spend a great deal of time reading and studying so you can answer every question that will come up. Don’t try to memorize it just remember where to find the material on that issue.
This is just a start. Now you need to know what Piping Code will be the basis for the project.
Will the project governing Code be:
• ASME B31.1
• ASME B31.3
• Or some other Code?

Now the next thing you need to know is the Clients preferences and or restrictions. Things like does the client want to use “Lapp-Joint Stub-End” flanges in certain systems. Does the client want or not want certain types of valves (and why)? What about Weld-neck vs. Slip-on flanges?

Next you need to know the “Design Life” of the plant. This means you need to know how long the plant is supposed to last before it is shut down or starts to fall apart. This issue determines the amount of corrosion allowance you will consider when selecting a wall schedule.

There is no doubt more that I have forgotten to include in this first pass. I will try to add more as I remember. I also know that by posting this here on the pipingdesigners web site others will read it and ad their wisdom.


The finished “Line Class” pipe spec.

Each of the individual Line Class sheet might be created as a spread sheet in a Microsoft Excel Work Book. One spread sheet for each Line Class.
Across you might have the following column headers?
• Item
• Nominal Pipe Size (inches) or (Metric)
• Schedule (Wall Thickness)
• End Type
• Description (This is a simple description of a piping component not a full purchase description)

Vertically the first column (Item) will be divided into “Pipe”, “Fittings”, “Flanges”, “Gaskets”, “Bolts” and “Valves”
With-in this column the “Fitting” section and the “Valve” section would be divided to cover the various items normally required based on size.
“Fittings” would include:
• 90 degree ELLs
• 45 degree ELLs
• Straight TEEs
• Reducing TEEs
• Caps
• Unions
• Etc.

“Valves” would include:
• Gates
• Globe
• Check
• Ball
• Butterfly
• Plug
All of these valves would not be in every Line Class. So which valves does each line class really need?

Other information that needs to be included on a line class by line class basis includes.
• Basic Construction (2” and smaller Screwed/ 3” and Larger Flanged and Butt welded, etc)
• Flange Rating (150# RF)
• Temperature Limits (Minus 50 degrees F to Plus 500 degrees



This is a lot to worry about, and it takes a very special person to do it right. Also it is a full time job not one that someone does as a side line in their spare time.

 

[Drexl]

Pennpiper, thanks for a good post

 

[LSThill]

TECHNICAL NOTE:

PLEASE REVIEW THE FOLLOWING:

http://www.red-bag.com/

Pipe Class Component (PCC)

The PCC software is used to calculate pipe class components for internal and external pressure.

Click this link to view a 5 minute introduction to PCC.

PCC calculates components and complete pipe classes with the click of one button. The PCC calculations can be selected by the engineer from ASME B31.3 (USA), EN13480 (Europe), and RToD (Netherlands).

For basic feature information please review the fact sheet: A4 or letter (PDF 33kB)

Basic work principle of the application is indicated in the Getting Started Guide: A4 or letter (PDF 1.7 MB)

The calculation results can be shown in a summary sheet. Colors indicate the amount of design margin used. Reports and calculation details provide the engineer all information as is depicted in the design code. All overviews, reports and calculation details can be printed or exported to MS Office tools for further processing. Also import and export to XML format is available for interfacing with other software applications.

Prime goal for the development of PCC was the ease of use. Pipe classes consist of many components such as pipe, elbow, reducer, cap, tee and weldolet. The amount of components and the branches are handled in an efficient and structured manner. The presentation of the data has the looks of a pipe class specification.

For more information see detail PCC page on the menu at the left.

Public issue of the user manual


LEONARD STPHEN THILL