Old vessels MOCs- ASTM 212-B and A-455-B

[garfio]

I am looking for information about the MOC of two very old pressure vessels built to ASME BPVC Div 1:

1. Vessel built in 1968. Shell A212-B (1.081")
Heads SA 455-B (0.636")

2. Vessel built in 1962. Shell A 212-B (0.75")
Heads A 212-B (0.420")

Info from Forms U-1A.

I don't have available such old versions of the Code, so I need help/guidance to answer the following:

a) There is not MDMT reported. How can I determine the minimum operating temperature? In some forum threads I read about having -20 °F as minimum or -50°F if normalized, but
I have no info about heat treatment or impact tests. What would be the worst case MDMT?

b) I need the tensile strength reported by applicable ASME code. Also I need to confirm that the design factor was still 4 in those years (A copy of the code page with the info would be great, and believe that would be ok under fair use criteria). This is for purpose of cross-checking the information that I have available.

There is a thread in this forum that talks about SA 455 but does not mentioned grade "B", and wonder if there are different grades for it.

Thanks in advance.

 

[eliebl]

For the codes back in the 60's there was little reference to MDMT. The current MDMT rules did not come into the code until 1986 if I remember correctly. Prior to 1986 there were a few simple rules. Most materials could be used for temperatures down to -20 F provided they were less than 4" thick. If a temperature lower desired then impact testing was required.

As for the "design factor" it was 4 in the later parts of WWII with it being raised to 5 again after the war. "Great Advancements in Welding" was the phraase used to justify the lowering of the design factor to 4 permanently in the 1950's. It remained at 4 until the recent change to 3.5. It should be noted that the 4 and 3.5 are generalizations and do not entirely represent the inherent safety in the design.

For what it's worth I was asked a question about A-212 gr"B" a couple of years ago and was able to find out that it would be comparable to A516-70 today.

Regards,
EJL

 

[unclesyd]

SA-212B; C-Si; -20 to 650 allowable is 70,000/4=17,500

SA-455B; -20 to 650 allowable is 73,00/4=18,250 (this is the only value listed therefore limiting the material to 650F.
note (26) This material shall not to be used in thicknesses above 0.58". This may be alright as your extra may have considered a corrosion allowance to sneak by.

Both are P-1 materials.

These values are from the 1965 Code Book. Looking at some old calculations from around 1968+ the SF was still 4 confirming the post byeliebl.

There is an A grade for both alloys.

 

[garfio]

Thanks for the information.

In one of the threads there was a reference to the possibility of using A212B down to -50°F when in normalized condition. Is there any reference on the 1965 Code to this? For what I read in the answers, seems that the materials could be used only down to -20°F without an impact test disregarding of the normalization. In other thread it is mentioned that A212B spec required normalization above certain plate thickness, while it was optional for thinner plates.

 

[eliebl]

In the current code rules the addition of normalizing and production to fine grain practice allow a shift from one curve to another. These curves are part of UCS-66 so I do not believe that they were in existence in the 1965 code. Also, the provision to PWHT when not required is in UCS-68(c). This is another area that was revised or added in 1986.

EJL

 

[unclesyd]

The requirements for PWHT were given in UCS-67, Design, as follows.

(c)Vessels of welded construction shall be post weld heat treated in accordance with the provisions of Par. UW-40, unless the vessels are in a classification exempted from impact test by Par, UCS-66 (c). Exempted vessels shall comply with the post weld heat treatment requirements of Pars. UW-10 and UCS-56.

Essentially what the Code did was to say if you were going to operate with any materials in UCS-23, with a few materials not permitted, below -20F they would have to meet the more stringent requirements of normalizing, impact testing, and PWHT not required at -20F and above.

Allowable Stress Values.

UCS-67 (d) The allowable stress values to be used in design shall not exceed those given in Table UCS-23 for temperatures of -20F to 650F.

UG-84 (d)
The impact test shall be conducted with +/- 3F of the lowest temperature the material is expected to see in service or testing.

There was a Code case # 1518 concerning SA 455