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Techniques are constantly in flux In the manufacturing world.
There have been significant changes over the past few decades.
We’ve gathered up the most popular terms used in pressure vessel manufacturing and turned them into a helpful list.
Use it to build your vocabulary – and understanding – of pressure vessel manufacturing terms.
Here’s what you need to know.
The American Society of Mechanical Engineers (or ASME) oversees the standards to which various products are manufactured.
A pressure vessel is one such product that is designed, manufactured, and tested in accordance with the ASME Boiler and Pressure Code.
This is a standard created by the American Society of Mechanical Engineers (ASME) that controls the design and construction of boilers and pressure vessels. Pressure vessels that have a door on one end fall under the authority of this code.
The primary standard for pressure vessels is Section VIII of the code.
The ASME code is written by volunteer expert engineers and is routinely reviewed and updated.
A pressure vessel that is designed with a quick opening or door.
The type of autoclaves Tank Fab manufactures use steam, pressure and differing exposure times to treat wood, vulcanize rubber, and create aerated concrete and fiber cement.
Wood, untreated rubber, or other items are arranged inside the autoclave and exposed to high levels of pressure and/or vacuum. After this process, the items are now “treated.”
Control systems that operate a process or system with little human interference.
At Tank Fab, our EASY Treat™ system automates the process that’s being performed inside the pressure vessel.
Pressure vessels or parts of pressure vessels that are prone to thinning by corrosion, erosion, or mechanical abrasion must be designed with increased thickness in those areas for additional protection.
If no corrosion allowance is included in the design of the pressure vessel, you’ll need to reduce the working pressure of the vessel once the material thickness is below the pressure vessel’s design thickness.
Design Pressure is also known as working pressure. It’s the desired internal pressure that the pressure vessel will work at while doing its job.
It’s important to note that design (working) pressure is different than Maximum Allowable Working Pressure
Door swing refers to the distance between the pressure vessel’s inner door face and the outside edge of the door when it is in the open position.
Also referred to as “ID,” it’s the measurement of the inside diameter of the pressure vessel’s shell and or head.
Also referred to as “OD,” it’s the measurement of the pressure vessel’s inner diameter plus the nominal thickness of the pressure vessel’s shell, times two.
Outer Diameter (OD) = Inner Diameter(ID) + (shell nominal thickness x 2)
Joint efficiency is used when designing the minimum thickness of the pressure vessel shell to be within the parameters of the ASME Code.
The code assumes that a welded joint is weaker than the material it is joining together due to porosity, slag inclusion, etc. within the weld itself. Depending on how the weld joint is going to be inspected via radiography, a percentage factor is used in the calculations for determining the shell and or head thicknesses.
You can check out this article by PV Engineering for more details about joint efficiency.
There are a variety of loadings you must assess when designing a pressure vessel. The ASME Code lists some of those.
UG-22 in section 8 of the ASME Code provides more information about this.
The manufacturer data report is the document that your pressure vessel manufacturer created after the pressure vessel was manufactured and tested in compliance with the ASME Code.
This document includes information regarding the design and manufacture of your pressure vessel.
Some of the information on the report includes:
Take a look at this example of a manufacturer’s data report.
It’s important that you keep this document for any repairs or alterations your pressure vessel may need in the future. Without it, you’ll have a hard time getting this type of work approved by your state’s pressure vessel governing body.
If you don’t have a copy of your manufacturer’s data report document, there’s a possibility you could get a copy of it. But, the process is rather involved, so keep that in mind if you find yourself in this position.
Maximum Allowable Working Pressure (MAWP) is the highest pressure possible within the pressure vessel when it’s working under normal operating conditions.
This is NOT the same as the autoclave’s Design Pressure.
As per the ASME Code, every pressure vessel must be installed with some type of pressure-relieving mechanism.
This is usually a pressure relief valve. The pressure relief valve is designed to start opening at 10% below the pressure vessel’s MAWP and to be fully opened at the pressure vessel’s MAWP.
This keeps the vessel from over-pressurizing which can lead to hazardous circumstances.
Maximum Allowable External Pressure (MAEP) is the greatest amount of external pressure, aka vacuum, within the vessel under normal operating conditions.
UG-28 in Section 8 of the ASME Code gives more information about this.
The important thing to remember is to look at the nameplate information on your pressure vessel. If there’s no information on the plate regarding MAEP, external pressure, Maximum Allowable External Pressure, etc., then your autoclave is not designed for external pressure use!
Doing so can cause the pressure vessel to fail. It’s important to consider this if you’re looking to buy a used pressure vessel.
Remember, not all pressure vessels are designed for external pressure (vacuum) use.
Minimum Design Metal Temperature is the lowest expected temperature your pressure vessel will work under during normal operating conditions.
This temperature can be found on the pressure vessel’s nameplate. If the vessel is used at a temperature lower than the one designated on the nameplate, your pressure vessel could be damaged. For example, cracking within the vessel’s weld joints.
Minimum Thickness is a measurement of the thickness of your pressure vessel’s shell and heads.
The minimum thickness standards need to be met so your vessel can withstand the loadings (pressure, internal weight, etc.) placed on it.
Section UG in section 8 of the ASME Code includes Minimal Thickness standards.
Nominal thickness is the minimum thickness of your pressure vessel’s shells and heads, plus any additional corrosion allowance that was included in the design of your pressure vessel.
You’ll find the nominal thickness your vessel was designed to on the Manufacturer Data Report.
This is a sub-assembly of your pressure vessel system.
The Material Handling System is all of the components used to move your product into and out of the pressure vessel. This includes the carts, tram cars, winches, and tracks the carts and cars move on.
Tank Fab also designs and manufactures these systems. This system has the possibility to increase your pressure vessel’s output production by more than 50%.
This is a number that’s registered by the pressure vessel manufacturer with the National Board of Pressure Vessel Inspectors.
By applying and registering this number with the National Board, it permits you, as the pressure vessel’s owner, to acquire a copy of the vessel’s Manufacturer Data Report in case you lose your copy.
If your pressure vessel was registered with the National Board, the nameplate will have a National Board number – sometimes called an “NB Number” – on the plate.
This is not required by ASME Code and it costs the manufacturer of the pressure vessel additional money every year to offer this service to their clients.
Here’s the link to the National Board’s site where you can order a copy of your pressure vessel’s report.
Non-Destructive Testing (NDE) refers to the different kinds of assessments your pressure vessel will be subjected to during the manufacturing phase.
This may include radiography, magnetic particle testing, ultrasonic testing, liquid penetrant testing, or hydro-static testing. The examination ensures that your pressure vessel meets the design and manufacturing regulations of the ASME Code before it’s shipped to you.
Track gauge is the distance between the inner edges of the tracks inside your pressure vessel.
This is Tank Fab’s tagline.
What does it mean?
When you work with us, you’re getting more than just the pressure vessel. You’ll also get all the piping, valves, pumps, automation, and instrumentation you will need to run your pressure vessel and process your product in the vessel.
We also provide the material handling system for your pressure vessel, if you need it.
Does your pressure vessel manufacturer do that?
Familiarity with these pressure vessel manufacturing terms and definitions puts you in a place to be the go-to source for the pressure vessel needs within your company.
You want the people who work with you to be convinced that you’re qualified to help them meet their goals.
Pressure vessel manufacturing terms and definitions are explanations of processes, functions, equipment and other relevant aspects of pressure vessel production.