Hello, im a welder trying to gain some more technical expertise. I've been studying code parameter and so on and recently came across to a table that explains the maximum reinforcement allowed on a weld. The table includes some values. My question is the maximum reinforcement allowed seems to change depending on the "design temperature". Whats is this design temperature? Is it the temperature the weld is going to be exposed to? This can be found on this pdf https://www.aws.org/library/doclib/cwi-partB-BOS-customary20170418.pdf on page 14, table 5. Thank you
The table you are viewing is taken from the AWS "Book of Specifications" used for the CWI exam.
This is not an actual working specification. It is a simulated code/specification and the section you are viewing is dedicated to pressure piping.
The book of specifications (BOS) has several different codes within it... (Structural, Piping, Pressure vessels) and they are to be used with mock-up weld samples and mock-up welding procedures and PQRs by test takers to prove they can navigate numerous codes that have differing acceptance criteria.
The table you are viewing in essence is not a real table... However it might closely resemble API 1104 piping specification.
As to your question about design temperature... I think you are probably right to assume that the temperatures they are noting are what the weldment would see in-service.
As Lawrence said, the table is from the Book of Specifications used for the Part C CWI examination. The table is modeled after ASME B31.1 Power Piping Code. The B31.1 Power Piping Code covers the type of piping typically found in a power house. Think steam lines if you will. Steam pressure goes up as the operating temperature increases. Think of a pressure cooker. The water boils at 212 degrees F at sea level. As the temperature in the pressure cooker increases, the internal pressure increases as well.
In the case of power piping, the same principles apply. The concern is that the greater the weld reinforcement, the more notch-like the toe of the weld becomes. It becomes a severe notch-like stress riser if the height (reentrant angle) is not controlled.
The maximum design pressure is the pressure used when the designer is calculating the wall thickness of the pressure vessel or the piping system. The maximum design temperature of steam dictates (for all practical purposes) what the design pressure is. Again, B31.1 is primarily the design/fabrication/welding/inspection criteria for steam lines in a power house.
"I'm alright," I shout as I stand up and brush myself off. "I just wanted to see if anyone was paying attention!"
I just heard from our old friend Stephan. He is doing well and finishing up his PhD in Welding Engineering. We don't hear from him because his is a busy lad with new responsibilities at work and serving as the chairperson on several international welding committees.
I will say that I miss his participation in this forum.
Thanks for the update on our buddy Stephan. Glad to hear that he is doing well. Busy is usually a good thing, so we can forgive him for not dropping in to check on us here in the forum.
Thank you for your reply. But just to make sure i understand, the temperature on the table the temperature that the weld is going to be exposed to while in service, or is it the temperature of the system which by being higher would generate more pressure on the pipe or vessel?
Assuming the heat is transferred through to the pipe wall (steels are not know for their insulating value), it would be the same from a design and code perspective.
I understand but to my question regarding a vessel or a pipe, would the 500° f be the design temperature. My exact question is, exactly what is the design temperature. Is it the range of temperature at which the vessel or pipe is going to operate? Is maximum design temperature the maximum temp to which it might rise? And if its not, what exactly is design temperature...
I believe it is the maximum temperature used for the purpose of design calculations. The operating pressure and temperatures should not exceed the design parameters. It is best that you look in the applicable code and look up the definition of the term you are looking for.
Al
Thanks for the update on our buddy Stephan. Glad to hear that he is doing well. Busy is usually a good thing, so we can forgive him for not dropping in to check on us here in the forum. 
