The Authorized Inspector - Manufacturer Relationship in a Mass-Production Shop
The following presentation was delivered at the 80th General Meeting Monday afternoon session, May 9th, by Michael Pischke. It has been edited for content and phrasing. A slide presentation of his address can be accessed here.
Speaker Bio:
Michael Pischke began his career in the pressure equipment industry 32 years ago as a pipe welder. Ten years into the profession, he entered college to pursue his bachelor of science in metallurgical engineering, and later his master of science in material science.
For the past sixteen years he has worked as the quality assurance manager for Alfa Laval. In this position he is responsible for a program involving ASME Section 8, the NBIC, and ISO 9001 quality systems. He is also responsible for welding and NDE qualification programs.
Mr. Pischke is vice president of the Pressure Vessel Manufacturers Association (PVMA) as well as a member of the Advisory Committee for National Board's Board of Trustees.
MR. PISCHKE: I would like to talk about the relationship between the authorized inspector and manufacturer, especially in the mass-production facility. I'm going to speak primarily about pressure vessels, but the same applies for any similar production, as in heating boilers.
I'm going to begin with the traditional vessel manufacturing process, the shop inspection process, and inspector and quality manager roles. Then I will talk about mass production, its characteristics and history in ASME, code requirements, quality/inspection strategies pursued by manufacturers and inspectors, and everyone's roles in this process.
Traditional Manufacturing and the Shop Inspection Process. As all of us know, the system we have in place has worked very well for decades. In a shop inspection process, the inspector would normally review design calculations, establish hold points in the production, verify material marking and documentation, witness weld joint fit-up, inspect final welds, and verify any postweld heat treatment or NDE results and records, if applicable. Additionally, inspectors would normally witness pressure testing and final stamping – something that happens in shops all over the world for custom vessels – and they also monitor quality systems on a regular basis. This list doesn't cover every scenario. Each factory is different and each product type is different.
Authorized Inspectors. The authorized inspector is normally trained by the employer or the National Board. I would be remiss if I didn't mention that many of the inspectors here and across the world have had extremely valuable, primary training by the navy and the military in general. However, there is a decrease of boilers in the navy, resulting in a decrease in that particular training, which I feel is very unfortunate.
Authorized inspectors are tested by the National Board. They follow inspection criteria based on the code. The criteria are laid out pretty clearly in the code and they rarely vary too much from that.
They work closely with the quality manager. This relationship is extremely important. In fact, I would say if this relationship is not working well, the whole system is in trouble. The inspector and quality manager need to understand how to work together, even if they don't always agree on everything. And no two people will ever agree on everything, but they have to make it work.
Quality Managers. The quality manager reads the code books. One thing we love to do is read code books, especially when somebody from marketing or sales comes in and says, “You read the code, don't you?” I say, “Yes.”
That usually means they have done something wrong or sold something we couldn't do, and we have to go back and read the code book together. Quality managers serve as liaisons with the authorized inspector, as I mentioned before. Oftentimes, quality managers were former inspectors, either an authorized inspector (AI) or a line inspector with the company. It's often where they come from, and perhaps they may be a level three for their company. Most quality managers, me included, come from a background of inspection and rework, and not so much in methodology of preventing quality errors.
Pressure Vessel Mass Production and Characteristics of “Mass Produced.” We discussed the typical custom vessel, one-off shop, and now we are going to talk about the mass production. The characteristics of mass production include standardized designs, often modular in nature, so that you can get the most variability with the standard design aspects. Materials are typically purchased in quantities from limited sources, what we call strategic supply. The purpose for this is two-fold, and you may think it's for price, but it's more for reliability. You want to get a supplier who can not only supply material that is good at a fair price, but you are also looking for a supplier that can continue to supply the material. Because when you are in a mass production shop, the material has to keep flowing or you stop producing.
It's always good to have multiple suppliers. Typically my company tries to get two suppliers for each component, so if one supplier has trouble delivering, we can always lean on the other supplier to get more products.
Another characteristic of mass production is repetitive fabrication processes. Fabrication processes are the same almost day in and day out. You rarely have new processes, with the exception of strategic ones. And I will talk a little bit more about that later.
Mass production also has a large experience base, good or bad. When mass-producing a product and there is a defect, you are mass-producing defects. So in a mass production, you try to avoid those at all costs. Therefore, what I really want to emphasize is that mass production requires a different quality approach than custom vessels.
History of Vessel Mass Production in the ASME Code. It originated in 1962 and found a home in Section 8, Division 1 in UG90(c)(2) for many years, known as multiple-duplicate. A good friend of mine from the inspection agency said this about multiple-duplicate: “Multiple-duplicate is like childbirth. It's a beautiful thing, just not something everybody should be watching.” I wasn't sure what he meant at the time, but later on I believe what he meant is if you look at it from the eyes of a custom vessel person, inspector, it may appear to be overwhelming and disturbing.
In 2008, the code was revised with the addition of Appendix 35. We moved many of the rules from UG 90(c)(2) into Appendix 35. And after that we changed the name to mass produced. We felt it was much more appropriate for several reasons; one being that internationally, mass produced is a more common term. But also multiple-duplicate is not really an accurate term for what we are doing.
Current Code Requirements in Section 8, Appendix 35. One requirement is having a full-time inspector. Many people may believe the reason for this is if production is low enough, the full-time inspector can revert back to the normal inspection processes. For some people that may be their strategy. But as you will see, inspection strategies with mass production need to change. Another requirement is the rate of production that makes it “impracticable.” That word is very vague and subjective to who is using it.
Another requirement comes from the term "shall be identical except." This was in the old code; we kept it there. And I'm not sure why we keep it there, because mass production isn't necessarily about whether you have two or three nozzles on a vessel, or the like. I think "shall be identical except" is confusing. Automobiles are mass produced and this is a perfect example. Are they the same color? Do they have the same engine or transmission? No. There is a lot of variability. The only thing similar is typically the name of the vehicle. Some of them with the same name don’t even look the same.
Another requirement is a minimum of two vessels per shift. They felt that if you were mass-producing something, you have to produce at least two vessels per shift. Again, the heart of mass production isn't necessarily the number of vessels per shift, but that's neither here nor there.
Another requirement is having a set quality control procedure. And that goes back to the repetitive nature of mass production. That's what we are trying to control. These rules also give provisions for data reports. It allows multiple units to be reported. And finally, there are special rules for pneumatic testing.
These rules were basically folded in from a couple of long-standing code cases that had been out there for many years. And so at this time with the rewrite, we decided to try to fold these code cases into the code.
Quality Strategy for Mass Production. This varies from custom vessels. For custom vessels, the typical approach is to inspect and rework. And this works very well for a custom vessel. In fact, this is optimum. And you either have something that's acceptable or unacceptable. If it's found to be unacceptable, you rework it, and then you fix it, and then you are allowed to ship the unit.
Mass production is a whole different strategy. I gave some examples of methodologies or tools of the trade for evaluating your production process to try and eliminate the number of errors you find in your process, let alone fix in your process. And so the strategy is not to go from unacceptable or acceptable, but the goal of perfection.
I'm going to repeat what a couple speakers have already talked about today in terms of trying to achieve perfection. We can try to eliminate opportunities for errors, and oftentimes that means eliminating production steps. A good example is if you are moving material around, you have just introduced a new chance to damage that material. But if you change your production layout to eliminate moving around material, you have just eliminated a source of errors; oftentimes a very bad source of errors.
Inspection Strategy for Mass Production. W. Edwards Deming, in his Inspection Strategy for Mass Production, said, “Cease dependence on inspection to achieve quality. Eliminate the need for inspection on a mass basis, “ – I want to emphasize that, on a mass basis –“ by building quality into the product in the first place.”
Now, that's a real nice sentence and it's much easier said than done, but we do want to eliminate the need, not eliminate inspection. By all means, we want to use inspection. But when you look at 100 percent inspection in a mass-production shop, if you ask the statistical quality people how effective 100 percent inspection is in a mass-production environment, they will tell you it is only 80 to 85 percent effective.
Now, what happens if you double your inspection requirement or your inspection force? If you get two people looking at it, you would think it would go up, but that's not what the statistical guys say. They say it actually drops when you get two people inspecting the same thing.
One statistical quality expert I read about said if you want to test this, take ten identical accepted parts (verify they are acceptable), and then take ten inspectors and have them inspect those ten parts. When you look at the reports, you will find a variety of differences. If you want to make it especially interesting, tell them that five are rejectable even though all of them are accepted, and see what the results are. You will see a lot of variability. In mass production variability is the key. You want to reduce variability.
What Processes to Inspect? In mass-production inspection, we want to inspect the same critical elements and processes that we do in a custom vessel. Such as incoming material reliability, prep and fit-up operations, welding processes, welding operators, examination and testing, and any other critical process related to that particular product. And note I said process, and that's what we are inspecting. When we inspect the product in a mass production, we aren't inspecting the product for itself. We are inspecting the processes. So if you are inspecting fit-up, you are actually inspecting the fit-up process: are the fixtures correct, are the fixtures worn, is the person doing the fit-up new, is it somebody different, and so on. You may be looking at the product or the part, but you are actually inspecting the process.
How to Inspect. So how do we do this? First, the inspector and the quality manager (and anyone else critical to the whole process) need to understand the manufacturing processes and know the variability of these processes. And that's one important thing about having a full-time authorized inspector. I know there was a lot of debate about it when we rewrote the rules, because there was nothing in the rules before about a full-time authorized inspector. But I think it's actually quite critical to have somebody there who understands the manufacturing processes very well. I know there are some other drawbacks to having the same person there all the time, but I think in the end it's best to have somebody who knows the manufacturing processes, and more importantly, who knows the variabilities; knows the weak points of the processes and what to focus on.
From there, develop a sampling plan. We still want to do inspections, but we want to focus on the areas that require focus. Adjust the plan based on changes in materials, personnel, or processes. An example of this is if the company gets a new supplier of material, it's good to focus on that area for a while until you get comfortable with that supplier. If there is a new qualified welder new to the manufacturing process, you may want to keep an eye on that person's work so you know they understand their duties and responsibilities. And like I mentioned before, inspect the product as a measure of the process. That's what we are looking at in mass production.
Communicate Inspection Needs. Our company has a cell status board. It is our way of communicating what's happening on our shop floor, and they are in each work area. Each group every day goes through the cell status board, and if there is any kind of issue, it gets put on the board.
And we have a hierarchy of importance. Of course, safety is number one, quality is number two, delivery is number three, and cost is last, number four. Anything on the board that is a safety issue gets the highest priority. Anyone in the plant is allowed to write an issue on the boards. And if that issue is written on the board, the team manager then writes it in their log and communicates it to all of the people that need to be there.
Our inspector can use the cell status boards for two-way communication. If an area is having difficulties with material or something else, our inspector can review the board and be informed of it. On the other hand, if our inspector sees a problem, he can also put it on the board and it needs to be addressed. So that's just one example of communication methods. But either way, in a mass production, each inspection needs to be communicated.
Finished Products. What we want from finished products in a mass production is for the first one to be the same as the last. We want very, very little variability. If we have little variability, then we can accept that if we inspect one of them and it's good, they are all good. And that's the goal, and not just in pressure vessels, but in any kind of mass production. I have had the pleasure of learning a lot about mass production in the last several years. It's been quite an education for me.
In Summary. The manufacturer and authorized inspector need to work together to identify critical components and processes that produce the vessels. They must shift from inspecting individual vessels to inspecting production processes. That doesn't mean you don't inspect the vessel; it means when you do, you are looking at it from a process standpoint.
They must spot check at different stages in production. Oftentimes, if you catch something early on, you can prevent a lot of errors. As I mentioned before, in mass production, if you have an error, oftentimes you have mass-produced that error. So the earlier you can catch it, the better.
Manufacturers and authorized inspectors work together to focus on the areas of high variability. Like I mentioned before, if you have a new material supplier or if you have a supplier who’s having trouble supplying consistent material, you focus on that. If you have a new person on the job, you focus on them. In today's economy a lot of shops have laid off, and now they are getting busy again and bringing in temporary employees.
And finally, the manufacturer and authorized inspector should communicate changes. It is very important for an authorized inspector and the manufacturer to work together on a communication method. All of us are working toward the same goals. Safety is number one. I think most pressure vessel manufacturers take safety very seriously when they get their code stamps. Thank you.