Welding in Sanitary Pipe

[mvor]

Hi,

I work for a pharma company that is in collaboration with a company in the Far East. The far uast company has built a new manufacturing plant and I recently visited. While in the plant, I noticed that the welds in the SS316L pipes did not appear smooth and had a slight discoloration (on the inside). The welds were also visible on the outside of the pipes (melted metal appearance). 304 was also used for some utilities, such as the CIP system. The same welding issues were seen in 304. The welds also came into question because we saw metal particles in equipment after running CIP tests. My question is: Can something like this go through an FDA inspection? My guess is no... What can be done to correct it? I realize that there is little information in this message to fully address the question. But any thoughts would be appreciated.

Thanks!
MVor

 

[FrancisL]

As I understand, it's not up to the FDA. If your company can validate the installation and prove it is OK then the FDA should not be a problem provided you have done the validation right.

 

[bsg]

Dera mvor,

Let us address the issue from other way.SS 316L Sanitary fittings are very costly. There is absolutely no point if someone uses these fittings and then do not use proper welding techniques. The very purpose of using these fittings is lost if rough uneven surface is generated through these weldings.

There are differnet methods of welding ss 316L pipes and number of specalists are there. One of them is ,of course, Alpha Laval.

Regards,

bsg

 

[DavidG14]

It is normal to see weld lines but you should not see discoloration. Discoloration is indicative of poor welds.

The only way to fix poor welds is to cut them out and redo them. Automatic orbital welding is the preferred method of welding sanitary pipe. Welders must be qualified and it is important to have an inert atmosphere or all kinds of undesirable oxides will form during welding and show up as heat tint.

EP is the prefered finish for product contact surfaces.
MP might be OK for a once-through CIP system changing to EP when joining product contact surfaces.

Your CIP fluids may be the most corrosive in the facility so 316L SS is a far better material choice than 304L. So much of the cost is in the fabrication that the higher grade stainless does not result in a significantly higher total cost.

Has the system been passivated?

 

[MedicineEng]

mvor:
All the above mentioned advises given by the other members are valid, I just wanted to add a couple of more issues:
It is tipicall that you proceed with some X-ray tests to assure that the weldings were well done. Last year I was in charge of a PW system installation and what we did in the PW loop was to have 10% of the weldings X-ray (random choice). If any of these weldings was failing the X-ray, we would redo the defective welding and make an X-ray of the imediate previous and following welding to check if that was a one time error or if it was repeating. And so on. There are companies that perform these tests and give you a report in the end with the results. Auditors like that.

Other care that you should have is if you are welding with material addition is to make shure that there are no mix of welding rods (like welding 316L pipes with 304 welding rods)

Are you shure that the particles that you observed came from the pipe? Couldn't it be form the drums where you receive your CIP solution?

PR

 

[EdStainless]

A lot of systems have 'issues'. These are usually addressed by chemical cleaning and re-passivation. Then, if people are concerned they install point-of-use filters that they inspect periodically.
As long as the water quality meets your validation criteria you should be OK.
The real risk is that you will start to experience rouging much earlier in this system than in one that was properly welded. Though I will say, in my experience almost every rouging case is realted to poor quality pumps.
Stagnant CIP solution in 304? I hope that you already have replacement plans, this will go quickly. I have seen 2205 and AL-6XN used for handling CIP solutions.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[HEC]

MVor,

I have worked in several industries, including the Pharmaceutical Industry. One thing I have noted is the propensity to use inapropriately high standards for applications. What is the application for the process and CIP lines? This question must be answered before the apropriateness of the weld quality and finish can be commented upon.

In general, and I dislike general statements, only sterile processes require orbital welding and EP finish tube. For oral dose and creams a high standard of manual welding with MP tube is acceptable. The use of orbital or machine welding is to ensure repeatability of the welding process. An orbital welder if set up incorrectly can cause welds of poorer quality than a proficient manual weld.

The installation and quality or build standards should be appropriate and adequate for the purpose. In relation to FDA, Australian TGA or other reglatory approvals having a design, install and commissioning paper trail is more important. This is the Design, Installation and Operation Qualification documents.

Hope this answers some of your concerns.

Mark Hutton
hutton4eng@picknowl.com.au

 

[EdStainless]

Mark, you have hit on a real issue. Many Pharm customers have not done a good job of dividing their plant systems by the type of serivce and then setting criteria for each. They try to use one material (usually 316L) and one set of instalation/inspection criteria for everything.
A good example is CIP solution delivery systems and hot water systems. Neither of these has the hygenic demands of product systems, but they significantly different corrosion issues.
I must addmit that I like people that insist on putting hot water in 316L, it keeps me busy.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[MedicineEng]

Ed:
What do you mean with "I must addmit that I like people that insist on putting hot water in 316L, it keeps me busy."
Is there any issue with 316L and hot water?
I ask you this because I work with PW systems and the basic sanitization of the distribution ring is with hot water at 80C or 121C (if you want a "sterilization"). I already have contact with these systems for the past 6.5 years and I never heard or experienced any corrosion problem with the sanitizations.
In fact, I believe that most of WFI systems that work by redestiling PW are made of 316L. and in this system I only experienced a problem once ( a cracked weld)in a system that was already 10 years old.

 

[quark]

Sometime back there was a row about SS316L and SS316Ti being MOC of lyophilizers and the metallurgy forum was quite helpful to me. Yet the decision went in favor of SS316L due to the obvious reason stated by EdStainless.

Till 8 years back, I saw, good many companies using boiler steam for autoclaving and the pipelines were made of carbon steel. They used to put a filter before autoclave and then it was an SS304 line with manual TIG welding.

With the advent of orbital welding, the repeatability increased and the process can be well documented. Once the sample pieces are welded to the satisfaction of the inspector(which is highly subjective), the print outs of welding parameters can give us some assurance.

Validation is a key criterion when dealing with regulatory authorities and I strongly feel no authority can dare specify a single material or a single process. But they sure feel that it is better to walk in a path already laid and well maintained.

Paulo,
The links shows EdStainless works with a tube manufacturing company and that is why he says we are keeping him busy. It is about time to ask for royalties, ain't it

Regards,

 

[EdStainless]

Paulo, To keep it short, Chloride Stress Corrosion Cracking.
In general WFI systems aren't a problem. But if the system will get hot with any residual chloride level things start coming apart quickly.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm