piping technical specification? 5

[johnmam]

first to say hello everybody because it´s my first time in this forum, second my question:

I want to do a piping technical specification for piping system of a power plant so I´m using the code asme b31.1, I know how get the rating for a piping service from asme B16.5 but a I have no idea how carry on, I don´t know how select the corrrect schedules. I know to calculate minimun thickness wall but not how to apply this to do the piping technical specification.

I´m a beginner in this. Sorry about my english, i´m a beginner too.

 

[kepharda]

I am no old pro at this but as no one has had a chance to offer any advice I can at least get you started with some things to think about.

First making sure you have the minimum wall thickness calc correct. It sounds as if you have done this already. Ensure you consider the pipe joining method in this calculation as well. i.e. welding, threading, brazing, flanged, as it can effect the schedule you end up with.

Second, is to determine the minimum schedule that would enable you to meet the thickness requirement in step #1.

Third, take into account how much strengh you need from the pipe itself. i.e. If you need really long distances between the supports or heavy equipment is to be attached and supported generally you need a heavier walled pipe.

Most, engineers already have an idea of this at the begining, but make sure that the material type in the schedule of pipe you want to specify is readily available locally.
Generally only a few of the size/material/schedule possibilities are available and economical; -so find out what you can easily get.

 

[metengr]

johnmam;
My advice is to hire an engineering company that can develop this specification working with you. This is the way to learn how this type of work is done. Technical specification development is not for begineers or inexperienced engineers.

 

[pipehead]

typically the spec has all the items in it. It states flange rateing, gasget materials, thread lubricants, bolting sizeds and grade, valve ratings, elastomers allowed, inspections required, NDT required, welding proceedures, coatings and paint, along with what was stated by others.

 

[Gator]

What are the fluids, temperatures, pressures and flowrates? That's the first question. Do you have a P&ID or at least a PFD?

 

[johnmam]

thanks a lot for yours replies. My fluids is a thermical oil working at 750 F and 350 psi. The flanges rating i think is 300 for material group 1.1. I don´t have p&id yet my colleges are working in this, Idon´t have PFD, how both pid and PFD can help me for the spec.

to be more specific I want select a schedule for each DN

1"-21/2" sche 80
2"-14" std
ect

but i don´t know which criterium folow for this.

thanks again for yours opinions, i´m wondering it.

 

[BigInch]

You only need the PFD to confirm design pressure and temperature.

Most std piping specs would be based on running at a maximum ANSI Flange pressure at a given required maximum temperature, to which that spec would apply.

For example, you wish to write a spec to cover up to the maximum pressure allowed by ANSI#300 Flange ratings over temperatures of 0 to 120ºF. You extract the maximum allowable Pressure and Temps from the ANSI Flange rating tables, then get the maximum allowed stress for all the pipe materials you wish to include, at your maximum temperature of 120ºF. Now use the hoop stress formula of your code to calculate the necessary wall thickness of each diameter using each included pipe material. Then do the same for fittings and appurtenances.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[RossABQ]

Errors or problems in the pipe specs can cause huge added costs during construction; if you don't pay someone else with experience to write this spec, as suggested above, at least pay them to review it before getting too far down the road.

 

[0707]

In addition to what RoosABQ said you should consult existing power plant P&I`S, if it is a revamping, to find the piping classes. With the pressure and temperature, from existing, piping classes you can extrapolate pipe materials, ratings and schedule thickness for the same conditions of your application. As a rule of thumb thickness are defined by Barlow’s formula plus corrosion allowance plus a safety coephicient of 12%, then you should go to the market to chose the pipe schedules which equal, or are immediately above your minimum Barlow’s calculation.

Regards

luis marques

 

[johnmam]

I´m very grateful for yours replies.

I want to do the piping material and valve specification, in my first post I wanted to mean it, i don´t know if I got it, sorry again for my english. Anyway, I´m going to do this and it will be supervise, don´t worry the work will be a proper one. But I need to do it first. I´ll try do a proper one too, course.

At this point my problem is that I don´t Know how to do the pressure-temperature rating for the pipes, in fact i don´t know if there is one or I have to use the flanged one. How you can see I´m a bit lost.

Thanks in advanced for any reply. I´m studing information relative with the post as well to improve my Knowlegde, so any post is wellcome.

 

[LSThill]

Team Memgers

Reference PIP.org Piping Classification Specification

http://www.pip.org.

 

[johnmam]

hello again,

I have been studing about the topic, I checked the pip.org web and I found a good example of piping material and valve specification, thanks fot the link, now I know that thare aren´t any pressure -temperature ratings for the pipes and it must be calculated so How can I calculate the pressure-temperature ratings for the pipes? I know the design temperature.

thanks in advanced, johnmam.

 

[DSB123]

johnmam,
You generally do not calculate pressure-temperature ratings for pipe. What you need to do is select the applicable Design Code, depending on the process (or the Client requirements) and then calculate the required pressure wall thickness based on the formulae from the Code, the allowable material strength from the Code at the applicable design temperature and the design pressure allowing for whether you intend to use seamless or welded pipe. Once the minimum pressure wall thickness has been established add to this the applicable corrosion allowance to arrive at the minimum thickness. Then all you need to do is select a pipe schedule which when the applicable mill tolerance is deducted from the nominal thickness is greater than the minimum thickness(pressure thickness plus corr allow). All you need to do then is perform branch reinforcement calculations where you intend to use anything other than proprietary fittings for branches.

Simple really if you are experienced. Be careful there are pitfalls. Recommend you seek the services of a professional piping engineer or at least let one cast an eye over what you are doing.

 

[johnmam]

thanks for the reply, I´m carring on learning about this topic. I followed the processthat is described by DSB123, I can now calculate the schedule for particular piping, but if I want to describe schedules for all pipes for a particular services, e.g.

service: .......................

dimension material schedule rating
1/2"-2" A106 XS 150
.
.
.

And if I have, for instance, that calculate the pressure-temperature rating for pipes, How can I do this? Which cases are necesary to calculate it?

Thanks in advanced.

 

[LSThill]

TEAM MEMBER: "KISS" keep it simple

GOOGLE SEARCH FOR: Piping and Valve Specification, good reference Tool's:

ABB OFFSHORE SYSTEMS Document Title: PIPING AND VALVE ...
Piping and Valve Specification. 5060. ConocoPhillips Norge. Project. Rev.no. Rev.date. Page:. Of:. Section Overview. 02. 11.12.02. 1. 1. SECTION OVERVIEW ...

http://www.docstream.no/copno/5060/...

- - Cached - Similar pages

Also:

http://red-bag.com/

Pipe Class Component (PCC) software
Pipe lines in refineries and chemical plants consist of many types of components and sizes. During the design phase of a plant these components are selected mainly based on the design conditions of the process contained in the piping systems. The components are grouped in so-called pipe classes. The class defines the components to be used for certain process conditions.

I hope this help

 

[johnmam]

thanks a lot for your helpful post Isthill.

I looked for information in google but I didn´t find anythink so helpful.Actually, I´m reding all the information of those documents. just one question,it´s the same that in my last post because I haven´t found the answer in the documentes I have read.

And if I have, for instance, that calculate the pressure-temperature rating for pipes, How can I do this? Which cases are necesary to calculate it?

Thanks in advanced.

 

[LSThill]

johnmam (Mechanical)

Piping and Valve Specification,

Item 1) Limited by the Flange B16.5
Item 2) Limited by the Pressure not in B16.5, calculation THICKNESS of the pipe using ASME B31.1 OR ASME B31.3.

The reference is a example: ABB OFFSHORE SYSTEMS Document Title: PIPING AND VALVE ...Piping and Valve Specification. 5060. ConocoPhillips Norge.

John Breen, can give you more detail, search for Mr. John Breen posting on eng-tips.com or COADE Ceaser II form.

 

[bucs2047]

Johnmam

Standard pipe is manufactured to comply with ASTM standards, such as A53 & A106. I looked for the same docs online as I have in my books, however ASTM was looking to charge for the Standard Pipe Data Spread Sheet, which will give you NPS, Wall thickness, weight/ft, class, sch, grade, etc...

Maybe you could do a refined search or there's also the local library.

 

[johnmam]

thanks a lot for yours replies. I´m carring on with the Piping and Valve Specification. if anybody have some information that you think it could be useful, please, i would like to know it.

At the moment I have the same question that in my last post, I think I know how to do the specification basically but more I know more question I have, jejeje.

thanks everybody for yours tips.