ASME Specification For ID Controlled Pipes

Most specifications, whether they are ASME or API control OD, Wall Thickness, and Mass (when applicable).

For the pipes that you are referring to, where is the direction to control the ID originating from, the customer?

Often times, Customer Specs induce additional requirements that exceed industry standards. So long as the Customer Spec does not force an industry spec to not be obtainable, you have to meet both.

Hello Java Head

My ID controlled pipe demand came from the thermal power plants main steam and hot reheat steam pipe lines.Where we need a constant id of a pipe by which we can reduce the pressure drop ( one of many reasons to choose id controlled pipe)

If you use the same OD and schedule throughout each line of a given size, you could de facto have controlled ID.

Or you could go to tube.

Right... tubing, like maybe ASTM A513 T5 (DOM Welded) which is the spec for Tubing applicable for use in hydraulic cylinders and thus is ID controlled.

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OP, there are spec's for damn-near everything. I don't know what specs govern your application, but if the ID is critical then I think the spec would speak to it. I guess what I'm saying is, the 'general' spec for pipe is OD and Wall control. But there should be specific specs for your application... Like the tubing spec I mentioned above... a general spec for ERW Tubing is A513... but then there is A513 Type 5 which adds tighter tolerance requirements associated to drawing. And then there is Type 6 which has half the tolerance requirement of standard DOM but still with a wider micro finish range... then if you need a tighter micro... then there is a Honed variant… each with their own spec.

Getting back to Pipe, ASME B31 is the general parent spec for pressure piping, then it breaks down into sub-specs based on usage. E.g. Fuel is B31.2, B31.3 is Process Piping (likely a good starting point) Transport of Liquids is B31.4… but there is also API 5L and 5CT… and oh, there is also:

• ASTM A106/ASME SA106 B & C
• ASTM A53B/ASME SA53B
• ASTM A333/ASME SA333 Grd 1/6
• ASTM A335/ASME SA335
• ASTM A500 Grd B & C
• API 5L X52
• API 5L X42
• API 5LB
• ASTM A252 Grd 2 & 3
• ASTM A53 Type F
• AWWA C200
• NACE MR-01-75
• Ad nausea

What is the applicable industry spec for steam piping in thermal power plants? And not trying to be a smart-ass or anything… but if the applicable specs that govern your application aren't strict enough for you, then author a customer spec that each piece of pipe must fit within your tighter tolerance window of the general spec… I've been on both ends of custom (more stringent) customer specs… they're pretty common.

The code for BFW (Boiler Feed Water) & Steam piping is B31.1 I believe that its generally more stringent than B31.3 but I am only a process engineer NOT a piping engineer.

However I am still somewhat bemused by the insistence on controlling for id. As I understand the fabrication of pipe there is a fixed outer size and you use a different die in the centre depending on the schedule pipe to be fabricated which is why pipe has a fixed OD and a wall thickness. As noted above this does give you a controlled id.

You mention wanting to reduce pressure drop. I cannot see logically why this would need id control it merely needs a larger id. However please do NOT just reduce the wall thickness as this will reduce the strength of the piping.

Trying to second guess i think maybe you have a small increase in flow beyond the design of the boiler (or perhaps it is underperforming) and so you would like to get the required flow down a pipe of broadly similar size (so that it fits in the space available). However unfortunately as far as I am aware (and again this is not my area of expertise) process / steam piping is not fabricated on id so if you need bigger pipe you are going ot have to go to the next pipe size up which may give you all sorts of other problems.

If the boiler is not delivering the required flow at the required pressure there may be other issues have these been fully examined?

This could all be total balderdash and lead everyone up the wrong path it would help if you would explain why you feel that id controlled piping is important and necessary.

My requirement for a pipe is ID 355 and thickness 60 and material for the pipe is sa335p91, so as per the ASME/ANSI B36.10M I can't find the mentioned pipe.

And merits for the id controlled pipe:

a) I have a flexibility for selecting the optimum thickness as per my design rather than standard sizes mentioned in ASME/ANSI B36.10M

b) By this I will reduce the weight of pipe by eliminating the unnecessary thickness (if I select as pipe size as per ASME/ANSI B36.10M)

c) So I can reduce the load on pipe supports and hangers

d) For example I want id of 145 and thickness of pipe 8.5 so if I refer ASME/ANSI B36.10M I need to select pipe size OD168.3 thickness 10.97 which turn increase pipe weight and all consequence will follow.

At last I think I got my answer I referred the ASME code it says if I order a pipe based on id, the id should not vary more than 1% over or under.

Thanks for all your reply's

If you want to "reduce the load on pipe supports and hangers", don't forget to specify "light water".

This must be your first job.

Hmm I am still not so sure of the benefits here.

a) Are you sure about id 355mm wall thickness 60mm as this is a much heavier wall thickness even than Sch 160 / XXS which are the heaviest wall thicknesses typically used.

b) OK you can acquire an 'optimised' wall thickness. However this the offers you no flexibility if the process changes - temperature / pressure/ flowrate. What happens if next year you need 5% more flow and 0.5bar on the pressure?

c) yes you will reduce the weight but by what %. The safety margins on your hangers etc will probably tolerate the standard wall sizes. Also are you going to get bespoke hangers or are they standard sizes as well. If they are standard sizes then you wont save anything by having slightly lighter pipe. OK Just going on the 145mm pipe you cited there is a 15% saving in metal cross section so presumably that would mean weight as well so its more significant than I thought.

d) Have you looked into the costs of getting your own custom made pipe - both in terms of cost and delivery. It is likely that you are going to have to buy a minimum production run which may be much more than you need? Can you get fittings in the optimised wall thickness. These are often forgings and I think that would be more difficult to make than the pipe in your special wall thickness. If you have to buy standard wall thickness elbows and tees how will this impact your calculations. Similarly valves, flanges etc. With standard dimensions for standard pipe you cant quite just turn up and take it away but something along those lines but with bespoke pipe your delivery might be 6 months or more away.

a) Yes, the mentioned id and thickness are required for a 660MW boiler (pressure 270kg/sq cm and temperature of 560deg C)

b) The temperature, pressure and flow rate for which the pipe is designed are the maximum and not going to change in future.

c) " reduce the weight but by what %" I really need to calculate. My all hangers and supports are custom made for my pipe.

d) For this pipe I don't use elbows I use pipe bends and for reducers and TEEs I would fabricate as per the requirement of pipe.

Call your pipe a tube.

The first thing for ID control is to make ID<OD; otherwise, the hole will be on the outside.

To expand on Tornado's excellent advice,

1. All tube is to be made of a long hole surrounded by metal or plastic centered around the hole.

2. All tube is to be hollow throughout the entire length - do not use inside holes of different length than the pipe.

3. The ID (Inside Diameter) of all tube must not exceed the OD (Outside Diameter) - otherwise the hole will be on the outside. <per Tornado>

4. All tube is to be supplied with nothing in the hole, so that water, steam or other stuff can be put inside at a later date.

5. All tube should be supplied without rust; this can be more readily applied at the job site. NOTE: Some vendors are now able to supply pre-rusted tube. If available in your area, this product is recommended, as it will save a great deal of time at the job site.

6. All tube over 500ft (150m) in length should have the words "LONG TUBE" clearly painted on each side and end, so that the contractor knows it's a long pipe.

7. Tube over 2 miles (3.2km) in length must also have the words "LONG TUBE" painted in the middle, so the contractor will not have to walk the entire length of the tube to determine whether or not it is a long tube or a
short tube.

8. All tube over 6ft (1.83m) in diameter must have the words "LARGE TUBE" painted on it, so the contractor will not mistake it for small tube.

9. Flanges must be used on all tube. Flanges must have holes for bolts, quite separate from the big hole in the middle.

10. When ordering 90 or 30 degree elbows, be sure to specify left-hand or right-hand, otherwise you will end up going the wrong way.

11. Be sure to specify to your vendor whether you want level, uphill or downhill pipe. If you use downhill pipes for going uphill, the water will flow the wrong way.

12. All threaded couplings should have either right-hand or left-hand threads, but do not mix the threads otherwise, as the coupling is being screwed on one pipe, it is being unscrewed from the other.

13. All tubes shorter than 1/8in (3mm) are very uneconomical in use, requiring many joints. They are generally known as washers.

14. Joints in tubes for water must be water-tight. Those in tubes for compressed air, however, need only be air-tight.

15. Lengths of tubes may be welded, threaded or soldered together. This method is not recommended for concrete or earthenware tubes.

Courtesy of LynDoor™Industries.

PIPE is measured in O.D.

Tubing is measured I.D.

They do have an out of round tolerance for the ends and middle of the pipe.

It's adjustable.

Here's a micro-adjuster:

That's a micro adjuster!!!

What do use when you want to hit something really hard!

A Gallagher mallet.

Actually we run the pipe back thru the expander to round it out. Saves $. Most of the out of round is caused by handling not forming.

ASME sizing for pipes up to 12 inches are based on inside diameter and all larger sizes are based on outside diameter.

The wall thickness which will affect both ID and OD depending on pipe size, is determined by the pressure rating of the specific material used and the application requirements.

Reccently ran into simelar issues designing pressure vessels. I'll share how we resolved it:

First and foremost, for many ASME specs both pipe AND tube are dimensionally governed by OD and wall thickness. Switching between the two offers almost no difference, save for perhaps a miniscule amount of tolerance.

Per ASME, you can always specify tolerances tighter than the specs which govern dimensions, provided the new tols fall within the range of the old tols, in your design documents/drawings - this is actually written in to a number of the standards. The problem with this is it dramatically increases cost, as the supplier has to select/reject from thier stockpile to verify they meet your requirements.

When you boil it all down though, the specs really don't reflect reality. The problem is, the spec tolerances are overly generous.

When you actually measure the real parts, you'll find that the real variation on ID is significantly less than whats called out in the specs. For example, I was working with seamless 304/304L, 6" Sch. 40 pipe, which by spec has a tolerance stackup on the ID of about 7mm, but our measured samples only had a practical tolerance range of about 1.5mm. Given the standard deviation of our measurements, our sample size, and some backhand information that our vendor is getting material from multiple suppliers, I'm designing based on the assumption of a practical tolerance of about 3mm - less than half of what the spec calls out as permissible.

So, my advice would be, pick the specs based on the material properties you require, but get many samples and measure your ID's to determine what's ultimately practical. You may be chasing a problem that just won't really exist.

You are wrong Venu. The only parameter to define OD or ID is the diameter. Read again ASME/ANSI, or consult a tubular supplier.