Stainless Steel Pipe 5

[Tankman650]

I have a chart of pipe properties that indicates that the thickest 14" pipe for ss is 10S. The chart references ANSI B36.19 stainless steel pipe schedule numbers.

I have been told by our field services that stainless steel pipe can be purchased in sch 40S with no problem.

If this is true, why does the chart not show that sch40S is available????

TIA

 

[LSThill]

Tankman650 (Structural)

Reference to ASME B36.19M - 1985 TABLE 1 on Page 3 and Table 2A on Page 4 Schedule 40s 1/8" - 12"

Leonard@thill.biz

http://www.thill.biz

 

[Tankman650]

Isthill thanks for your response.

I understand that the standard lists sch40s up to size 12" pipe but I am asking if anyone knows if it is a problem getting a 14" pipe in sch40s??????

 

[wassermann]

Hi Tankman,
try Felker in Marshfield, WI. I believe they can supply up to 20" in Sch40.

Brian Hollingworth
Hastec Engineering
Ontario
Canada
hastec.com

 

[Tankman650]

Thanks Brian,

I have tried to contact them to see if the delevery for sch40s is a problem. I understand that not all warehouses stock these sizes.

 

[mikedavy]

At 14", stainless wall thicknesses change from Sch40s to Standard wall, the same as standard wall carbon steel.
14" pipe is available in standard wall from Bristol Metals in Bristol, Tennessee.

 

[unclesyd]

A General Note of Caution

Beware of welded S/S pipe in larger sizes. We had trouble with Sch 40 and above welded pipe in the 6"-16" ranges. We had four documented failures in the factory welded seams on the S/S Sch 40 and Sch 80 pipe. All but one was caught leaking before there was a catastrophic failure, though in all cases it was coming, the whole longitudinal seam weld was bad. One case was a complete failure of the long seam in the pipe(6" Sch 40 304L) resulting in a EPA recordable spill. After determining the cause of the initial failure by metallurgical examination, extensive NDT was done on installed S/S piping especially in one very hazardous area. We probably had 10% of the pipe that had the lack of fusion defect requiring immediate replacement.

All the failures were lack of fusion in seam welds. We had one installed piece that had only 20% fusion in the weld, it was fused inside and on the cap. At the time this spool was fabricated we were only doing 25% radiography. This forced us to increase our inspection of all piping to 100%. It was a very expensive proposition at our site.

The pipe seam welds were not autogenous.

All the pipe had passed the specified hydrotest prior to and during commissioning of the area.

The plant is still checking incoming S/S pipe. The lack of fusion areas are very tight making it very hard to check by RT. Most is checked by UT. The fitters and welds watch out for anything while prepping the pipe for welding.

I checked and found out the site had received a bad piece of pipe (8" Sch 40 304L) in June of this year.

 

[MJCronin]

unclesyd,

Who manufactured this faulty pipe ?

What ASTM specification was it purchased to ?

Several years ago, pipe flanges in SS and carbon were supplied from China that did not meet ASTM standards and required expensive replacement.

Can you tell us more ?

MJC

 

[unclesyd]

I’ll have to check and see if I can name the producer, there was considerable dollars involved along with the recordable spill.

But I can tell you that it was a domestic producer.

The real problem was that the producer was not forthcoming with information. When the first failure occurred we were assured that they hadn’t seen this problem before. This turned out to be very untrue (polite) as information received shortly thereafter we received word that they were in ?litigation? with the government over the same problem, unwelded pipe seams, at Vandenburg Air Force Base. After confronting them with this information, they absolutely assured us that this was a one time affair and they had immediately corrected the welding and inspection problem. They assured us that this stick of pipe must have slipped thru the system. If we had the correct MTR this could not have happened unless the pipe had been lost at the factory as the dates between the Air Force Failure and our pipe date of manufacture was one year. As we were having our little contests we had a second failure.

This failure was the one that got us moving as this line had been installed for 7 years old. This was a little more shock than an apple on the head. This is when we started inspecting pipe in a very hazardous area and found the additional defects. All the defects at that time were in Sch 40 304/304L S/S. We later found a problem with 3" 304L Sch 80. The irony of this was that RT of the welds in this area had been cut from 100% to 25% due to the quality of welds we were getting at the time from our construction crew. If we had stayed at 100% we would have been appraised of the problem earlier. Some of the seam defects had intersected the girth welds.

The whole thing boiled down to that they were having and had been having welding problems for several years and their inspection procedures that they were using were incapable of picking up this defect. We didn’t want to think that something else was going on. The defects in some pipe were so bad that we had a saying, “Ray Charles could have found them”.

All the original defects were the same, lack of fusion on one or both sides of the weld prep. All failures were metallurgically examined. We saw that some of the pipe in certain areas was starting to fail from fatigue. We saw no evidence of any contamination on the weld prep. All chemistry was verified. The pipe we had installed had passed the design hydrotest prior to installation and the commissioning pressure test. Operating spools remove for repair were hydrotested to two times the design hydrotest with no leakers. They would not let us test to failure.
We were lucky in that we had a fully equipped metallurgical lab with knowledgeable people on site.

To get back in our graces the company sent a section 6" Sch 40 for evaluation, damn if this pipe didn’t have an injoureous defective in the weld.

I’ll check and see if I can give any further information. All the information was kept internally, for what reason I don’t know. Every pipe distributer in the area knew the company would not accept pipe or fittings made from this pipe, by this producer.

All the pipe at this site was ordered to ASTM A312 at the time. Most was off the shelf from different vendors.

 

[unclesyd]

Adding to my post of yesterday.

I checked this morning and was requested not to name the company. I got no explanation as to why this answer was given, knowing very well every piping distributer in this area knows this. All purchase orders dealing with S/S pipe from the site exclude pipe from this producer. If I still had access to my reports and photographs with samples from the museum I would probably be okay in naming the company with impunity.

Pipe from this producer is still not allowed on site. All piping whether stock items or fabricated spools is checked with both the MTR and stencil. Lack of stencil means rejection. This problem resulted in a policy change from an all domestic to a qualified producer program.

I checked with the engineers that design and analyze the piping systems to ascertain how much of this piping is still in service. Some areas where the process was deemed non-critical most of the defective piping was left in service, though monitored by UT closely through a plant wide inspection program. In critical areas all defective piping was removed. Critical meaning conditions that could possibly initiate fatigue.

Whether the problem with the producer still exist is not known as the policy is outright rejection without any testing. They still had a problem in 1990. In any areas on site where S/S piping is altered or repaired, the repair plan now includes PT testing of the weld prep.

I’m going to check with others who have left the company that were involved to see what their thoughts are on revealing the name of the company. I know the government revealed it in their report.

Standby

 

[unclesyd]

This is a matter of public record. A little lengthly but interesting. Same song second verse.

http://www.uscfc.uscourts.gov/Opinions/Horn/98/Mortenson.htm

 

[reichertc]

Thanks unclesyd. I'd give you more than one star if I could. Just had to defend a decision to specify A358 over A312 (welded), and I slapped a copy of those court documents down on my challengers desk. He changed his tune pretty quickly.

Always love to hear the technical reasons why we specify one material over another. I have to specify pipe and fittings for a living, but I don't have 40 years of experience in the field. Often, I can reason out why we pick one over another by reading the codes and standards, but my knowledge of failures in industry is fairly limited. Usually the older, more experienced guys don't have the time to dig out case studies like this to prove a position to me, and I just get answers like, "We've been doing it this way for 20 years, keep doing it." As a guy who is not an expert in metallurgy or welding, but needs to dabble in each to perform my job, I very much appreciate your response.

Any more references to case studies (and not just from unclesyd) on pipe/fitting/material failures is greatly encouraged.

 

[rothrock]

If the pipe was specified as ASTM A312, the specification may be at fault.

Here is a link to a very informative court decision:

http://www.uscfc.uscourts.gov/Opinions/Horn/98/Mortenson.htm

In the decision it states:

"ASTM A312 does not expressly state or specify requirements for the longitudinal weld, weld fusion and weld penetration other than to state in subparagraph 5.2, titled "Manufacture," that "[t]he pipe shall be made by the seamless or an automatic welding process, with no addition of filler metal in the welding operation." In addition, the ASTM Standard Specification A312 incorporated into the contract does not provide express criteria to evaluate partial lack of fusion, nor does it provide an express requirement for weld quality.

Defendant's welding expert Kenneth Coryell testified, upon questioning by Mortenson's counsel, that not only did the pipe specifications in the contract fail to specify weld quality, but also that the supplementary weld quality requirements were available for ASTM A312 and could have been incorporated into the contract specifications:

Q Are you aware, too, sir, that the ASTM A312 requirement or specification standard has no specific requirement for weld depth or penetration?

A Yes. There is no specific language to that effect.

Q Are you aware, sir, that there are some ASTM pipe standards that do make such a specific description of full penetration if that is what they want?

A Yes. In fact, the supplementary requirements to A312 have provision for radiographic quality that includes penetration in those criteria as well.

Q But no such supplementary requirements were required on the Ellsworth pipe contract, were they?

A It is my understanding that they were not. I have no firsthand knowledge of that.

One example of specifications with "supplementary requirements" cited in the joint stipulations is ASTM A358 for electric fusion welded austenitic chromium nickel alloy steel pipe.(5) ASTM A358 provides that the joints shall be full penetration double or single welded butt joints. A358 is welded using filler material which makes the detection of partial lack of fusion by radiography much more reliable. ANSI B31.3 does not prohibit A358 welded pipe for cyclic service."

I was astounded to learn a pipe manufacturer could deliver pipe with the longitudinal interior seam weld totally missing the weld joint. But they can and do.

It was the engineer's responsibility to correctly specify the purchase of the pipe. Using an ASTM spec may not be enough if critical supplementary requirements are not specified.

The military now requires supplementay RT and UT of it's stainless pipe for hydrant fuel systems.

 

[unclesyd]

We had the extra inspection requirements and paid for same on the A312 pipe we purchased. I'm try to find out what we called out on the specifications at the time. We had big and at times heated discussions concerning the pipe as described in A312. It came down to the meaning of “welded”. One would assume that there should be some semblance of a weld on anything you purchase as being welded regardless of the welding method . If you had taken this pipe and fabricated it by means of girth welds of the same quality as the seam weld and they would have failed with someone getting hurt you would be in world of hurt as far as liability is concerned. This is because you didn’t use the “best available practices”. Or in any case “reasonable expectations”. The “best available practices” really hits home in our state as it is a non-code state. In any piping system designed using the best engineering available to a particular set of conditions one would expect to have the capacity for an upset. No matter how in depth you take piping design and reviews there is always something unforseen that will upset the system, like an instrument man, electrician, upgrading a control loop, etc. In one particular case we had old A312 pipe that was 20 years old in the same loop as the failed pipe. Essentially the new pipe went out on the first or second excursion, one would have expected more.

It has been mentioned that this pipe wasn’t intended for cyclic service, which was very well known by our design people and never used in same. There was plenty of design experience as we had processes that cyclic service was the primary consideration in design.

Another point to make is the government backed off on this case from the initial go around and didn’t pursue others for reasons unknown except to a few people on soap boxes.

In my previous post I mention “they still had a problem in 1990". This should have read 1998.

Codes and Standards do work except some better than others.