Why does SA-105 always need normalizing

Why normalize

Often do foreign project friends will find a phenomenon, is the owner to the specification of SA-105 material forgings generally require normalizing.
So is the normalization of SA-105 due to the specification requirements or the improvement of the requirements?

Consider SA-105:

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As shown in the figure above, for the standard flange, take 300 # as the boundary, if it exceeds, normalize it. For specially designed flanges, normalizing is also required.
For general low-pressure equipment, flange normalizing seems to improve the requirements?
Is that true?

Can SA-105 flange be used as tubesheet or equipment flange?

More than ten years ago, we just started to make ASME equipment, generally using SA-105 / SA-182 flange as tube plate or equipment flange, and AI did not raise any objection.
Until one day, AI pointed out that SA-105 and SA-182 could not be used for tubesheet and equipment flange. Because it is very clear in SA-105 of Volume II materials that tubesheet and equipment flange are not applicable.
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The title of SA-105 / SA-182 is pipe flange, so it is only used for pipe flange. And the weight is even more mandatory.
The maximum weight is 10000 pounds. From then on, 105 is a passer-by.
So everyone changed to SA-266, but a lot of times, it is not convenient to use SA-266.
For example, for a low-pressure equipment with small diameter, it is reasonable to use pipe flange as equipment flange. Is it necessary to use SA-266 at this time? Obviously, it’s more reasonable to use SA-105 for all the flanges. Purchasing the standard flange of the same material directly saves money, effort and worry.

The circle of norms

The standard still leaves a way to recover:
In ug-6, for tubesheet or equipment flange using SA-105, there is a supplementary clause. If it is met, it can be used not only for equipment flange, but also for flange weighing more than 5000 or 10000 pounds.
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Ug-6, C (1), if used for small forgings, SA-105 can be used for tubesheet and equipment flange after normalizing.
Therefore, the supplementary answer at the beginning of this article is that if SA-105 is used for equipment flange, normalizing is necesSAry, but it can not be regarded as improving the requirements.
In fact, there are several requirements for normalizing the flange in II
For example, in 5.1.3 of SA-105, the equipment flange can be regarded as the flange with unknown pressure and temperature, and it needs to be normalized according to 5.1.
The chemical composition and mechanical properties of SA-105 and SA-266 are very similar. Sa-266 is used for equipment flange, which needs normalizing. There is no reason why SA-105 should not be normalized when used for equipment flange.
In addition, SA-105 forging normalizing requirements is not high, such as GB / T150.2 forging material, normalizing is the minimum requirement.
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Therefore, it is very reasonable for the owner to require all SA-105 materials to be normalized.

Hardness requirements of SA-105

A while ago, a strange thing happened. The chemical composition and mechanical properties of SA-105 forgings purchased by the supplier were all in conformity with the quality guarantee, and the only one that was not in conformity was that the hardness exceeded the standard.
In the specification, the hardness value is required to be between 137-187HB.
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In S1 of supplementary requirements, it is clearly pointed out that when the hardness is not in the range, it can be rejected.
The manufacturer said that the original hardness was normal. After normalizing the flange, the hardness increased. I hope I can accept the use under concession.
We discussed it internally, but it was not allowed in the end. On the one hand, it was against the regulations of the specification, on the other hand, forging hardness measurement was a routine operation. In the national standard, class II forgings are often used, but class I forgings have hardness testing. If the hardness is increased due to normalizing, either the material has problems or the heat treatment process has problems.

Source: China Flange Manufacturer – Yaang Pipe Industry (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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