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When to Use Seamless and Welded Pipe
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(Petroleum)
(OP)
24 May 23 06:59Hi Experts,I have to choose pipe welded or seamless for raw gas but it's for 10 to 15 years not more than that, its API 5L X42 fluid is corrosive, no high temperature and pressure. I am looking for any reference from any standard which tells when to use welded and seamless or at least some valid technical points to defend my selection.Thanks in advance.
Replies continue below
(Petroleum)
24 May 23 07:33What design code?
How corrosive?
With what?
Size and wt affect availability. Above about 16 to 20" seamless gets hard to find
This is more of a material selection issue and I don't know if any pipeline code which will tell you this. B31.3 doesn't like welded pipe for some reason and applies a factor on wall thickness
There is a lot of preferential engineering here and different companies have different views.
There should be little difference but you may need to look at the impact of the seam weld on corrosion issues.
If you have sour service (H2S) then seamless is definitely preferred, which is a material selection issue under the NACE standards.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
(Petroleum)
(OP)
24 May 23 12:51LittleInch,
Its H2S rich
b31.8
8" size
Client will ask why I am selecting seamless or welded.
Thanks for reply
(Petroleum)
24 May 23 13:48You need to ask a materials engineer, but I'm pretty sure for sour service you need seamless if possible and 8" the cost is about the same.It's all about the hardness of the weld. Also look in your sour service specification.Design wise in 31.8 it makes no difference and they won't guide you as it is not something B31.8 does.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
(Chemical)
24 May 23 15:30A general rule for corrosive services is that seamless piping is preferred - ERW pipe tends to be attacked along the pipe-weld bondline at a higher corrosion rate than the base material. My impression (not fact!) is that mill tolerances for wall thickness are either higher for seamless pipe over ERW pipe or that they are harder to get within tolerance (more expensive). So if you need to do branch reinforcement calculations for larger diameters or higher T&P, the mill tolerance becomes important.
Piping codes don't generally tell you what pipe to use in a given application; there are generally too many factors and special cases, so they leave the application up to the user.
(Materials)
24 May 23 16:10Seamless will have much more variation in wall than welded.Seamless also usually has a rougher ID surface.In ERW steel pipe there can be selective HAZ corrosion attack because it isn't full body heat treated after welding.
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P.E. Metallurgy, consulting work welcomed
(Materials)
24 May 23 17:32For your application choose seamless due to answers provided above. Due to our global supply chain and the vast differences in ERW welding methods from mill to mill and quality thereof, a greater chance of failure is incurred using ERW. ERW pipe can be made with excellent properties but you really have to know the mill's capabilities.
(Mechanical)
24 May 23 18:13My two cents ...MJCroninSr. Process Engineer
(Chemical)
24 May 23 21:28MJCronin,
When would the MAWP of the piping become the deciding factor for a piping system's thickness at low temperature and pressure? In my mind, required thickness is often very low at low T&P, and other factors like maximum unsupported span and extra thickness for corrosion allowance tend to dominate. Typically pressure is also limited by the flanges or connectors rather than piping, is it not?
I'm not challenging you here, but rather curious as to where you've seen or heard of the extra MAWP of the seamless pipe being important in the selection of ERW vs seamless.
(Petroleum)
(OP)
25 May 23 06:47Littleinch, TiCI4, Edstainless, Weldstan, MJCronin
Thank you so much for your valuable time and information you shared, now its clear to me.
Thanks again you all
(Materials)
25 May 23 15:38At thicker walls the seamless premium is not very much more expensive.Many ASME codes do derate welded tube by 15% for no reason other than it was welded.The seamless tube will always be heavier and the thinnest spot will be thinner than with welded tube.The greater wall variation is just a fact of life.
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P.E. Metallurgy, consulting work welcomed
(Mechanical)
25 May 23 16:24For 10-15 years choose the cheapest.
Regards
(Petroleum)
25 May 23 16:29Each great project company in oil industry have its own basic engineering specs based on standaed codes, I am afraid you won´t recieve the wright answer here.
REGARDS
(Mechanical)
2 Jun 23 01:48Use seamless pipe. ERW pipe is not recommended in severe conditions. Welded point is weak points and it is at risk of failure
Daren!
(Structural)
2 Jun 23 04:09Quote (I am afraid you won´t recieve the wright answer here.)
... but informative, nonetheless.
-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates
-Dik
(Petroleum)
2 Jun 23 13:33Seamless steel pipe is better than welded pipe. Seamless steel pipe is limited in larged diameters up to 24".
(Mechanical)
Are you interested in learning more about Straight Seam Welded Pipe? Contact us today to secure an expert consultation!
2 Jun 23 14:37@
You are wrong.
See SA-106
1.1 This specifcation covers seamless carbon steel pipe
for high-temperature service (Note 1) in NPS 1/8 to NPS 48
[DN 6 to DN ] (Note 2) inclusive, with nominal (aver
age) wall thickness as given in ASME B36.10M
Regards
(Petroleum)
2 Jun 23 14:50r
you're right, I was speaking generally. But the use of welded pipe and seamless pipe depends on the intended service. If it is going to be used for a lethal dangerous, high pressure or corrosive service I would use seamless pipe, if it is going to be used in an enoquo service I would use the cheapest welded pipe.
(Materials)
2 Jun 23 15:33Seamless pipe isn't better than welded, it just has different types of defects in it.With welded you get very uniform surface finish inside and out along with very uniform wall thickness.The type of welding will dictate the nature of weld imperfections that you should be testing for, and the HT method (local to weld or full body) will influence the final properties of the pipe.Seamless pipe will always have very significant wall thickness variation (commonly over +/-10% in each length) and the ID surfaces can have significant variation in surface.Tears and cracks on the ID surface are not uncommon in seamless product.Seamless over ~24" OD is usually forged hollows made in short lengths.
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P.E. Metallurgy, consulting work welcomed
(Mechanical)
2 Jun 23 16:15Ed, thanks for that helpful explanation. I had previously assumed that seamless pipe was better than welded (in part due to the longitudinal weld joint quality factors in ASME B31.3), but your comment has helped me to better understand the differences.
(Structural)
2 Jun 23 18:00Quote (The type of welding will dictate the nature of weld imperfections that you should be testing for)
Ed...Can you elaborate on that a bit, or point me in the direction of some literature? This thread is not my type of work, but is very interesting. Thanks...
-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates
-Dik
(Materials)
2 Jun 23 21:01Since most of my last 30 years has been in SS and Ni alloys I'll speak from there.These are only fusions welded, no ERW and there is no filler used.So you have TIG, Plasma, Laser, EBeam, and variations/combinations of these.Traditionally the worry has been hot cracking of welds which tend to be transverse and this has lead to the very common use of Eddy Current testing. ECT will easily detect transverse indications with high sensitivity.However we know that all fatigues cracks will start at longitudinal indications. The only good way to detect these is using Ultrasonic testing.This especially applies to tubing that has been cold drawn where draw scratches and other issues will all be longitudinal.To put some scale to this when we make aerospace hydraulic tubing (welded and as-cold-drawn 21-6-9 SS) the UT uses notches that are 0.002" deep and 0.25" long, on both the ID and OD.All of our seamless tubing was UTed.And for highly fatigue sensitive alloys like Ti all tubing (welded or seamless) is UTed as well.Start with a list. what is the weld method and what are the most likely weld defects?What NDT methods are available (listed in applicable specs)? What will they detect and with what sensitivity?Also consider the impact of HT. In steels with weld-only HT there are a ton of local HAZ issues to consider.
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P.E. Metallurgy, consulting work welcomed
(Structural)
2 Jun 23 22:09Thanks, Ed... much appreciated... I owe you a beer...
-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates
-Dik
(Mechanical)
3 Jun 23 02:38Seamless pipe is the best choice for forming operations involving coiling, bending, etc.
Regards
(Petroleum)
3 Jun 23 07:58If the party responsible for purchasing the pipe is not operating a pipe mill appraisal scheme, and will simply go with a mill that is listed on the API Composite List, then it would sway the selection towards seamless even if it is more expensive. It will also aid inspection, should purchaser inspection be deployed, since there will not be any welding, and weld NDT, activity to monitor.
Steve Jones
Corrosion Management Consultant
www.linkedin.com/in/drstevejones
All answers are personal opinions only and are in no way connected with any employer.
(Petroleum)
3 Jun 23 12:35I agree with you SJones, you merith my star!
(Materials)
3 Jun 23 23:49r, not necessarily. The better diameter and wall uniformity of welded pipe often make it much easier to form.You need align the usage and the product."you don't get what you expect, only what you inspect"If you are not willing to send a specialist to the mill then you are agreeing to take the worst product that they might make.Even with seamless there is HT, lab testing, and NDT that need to be done right.
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P.E. Metallurgy, consulting work welcomed
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Which is better between seamless vs welded pipe?
Manufacturing
Strength
Corrosion resistance
Applications
Piping systems exist in almost any building or structure out there because of their innate usefulness. Whether they&#;re used to transport water or gas or for other structural purposes, you&#;ll find steel pipes on most construction sites. Pipe manufacturers do their best to meet the demands of the industry. They employ several methods to create different types of good-quality pipes. Because of this, companies find themselves wondering which is better between seamless vs welded pipe.
Seamless and welded pipes have many similarities. But as for pipe manufacturing processes, these two are commonly pitted against each other. Here, we&#;ll talk about their differences in several factors to help you make a more informed decision on which one is better. Keep reading for more!
The main difference between seamless pipes and welded pipes is in the way they were manufactured. To put it simply, seamless pipes are single pieces of metal with no seam or crease, or weld joint. Welded pipes are metal products that start as a strip that would be roll-formed and then welded to form a tube. Here&#;s how they are both manufactured:
The welded pipe manufacturing process has improved a lot over the years, making them less prone to corrosion and seam failure. Both seamless and welded pipes end up as a reliable part of the construction process, but different techniques are used to create them.
Thanks to its lack of a weld joint, seamless pipes are known to be very durable. It lowers the chances for corrosion and eliminates any weak spots along the tube. Seamless pipes are also generally heavy and thick-walled, contributing to their overall strength. A welded pipe&#;s working pressure is 20% less than that of a seamless pipe, and they need to be thoroughly tested before use to ensure that they won&#;t fail in the field. But because of the difficulty in manufacturing seamless pipes, their lengths are always shorter compared to welded pipes.
Welded pipes are typically lighter than seamless pipes. They also have tighter tolerances and are consistent in wall thickness, unlike seamless pipes which are not always consistent. Many innovations in the industry have also strengthened the weld joint more than what is historically known. Both are strong enough pipes &#; just pick the right one that fits better with your project!
Most customers will be worried about possible impurities in the pipe. That&#;s why seamless pipes are sometimes favored over welded pipes because it has no joint that could cause weakness or corrosion. The weld joint is considered to lessen the corrosion resistance of the product and create more dimensional variation than needed. If you manufacture an ERW pipe, however, the weld joint shouldn&#;t be an issue.
The two types of steel pipes being discussed here can be applied to many different industries based on their strengths and benefits. Seamless steel pipes have unique characteristics like being able to distribute weight evenly, withstand high temperatures and pressures, and others. This means they can be applied in industries such as chemical plants, hydraulics, nuclear power plants, water purification plants, medical equipment, oil and gas lines, and other similar applications.
On the other hand, welded pipes are ordered because they are cost-effective and can be manufactured in different shapes and lengths. Some industries that capitalize on this are architecture, aerospace, food and beverage processing, automotive, construction, and many more.
The debate between seamless vs welded pipe is an ongoing one because everyone&#;s needs are unique and changes are made every day. The answer to the question of which is better depends on your needs. Before making a decision, try reading the article again to see which fits your project best.
Whether you opt for seamless or welded pipes, you would still need to get it from a reputable company, like Supreme Pipe! We have been delivering top-of-the-line steel pipes to satisfy our customers since . Check out the products that we offer, and inquire now if you&#;re interested!
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