Question regarding the “manhole flange forging grade”
Thread Content
For forgings of primarily stressed components, GB/T 150.2 specifies that the forging grade shall be indicated in the drawing. For common components such as nozzles, flanges, end caps, etc., many of their part drawings are of custom-designed types; therefore, the forging grade specifications are indicated in those drawings. But what about standard components? For example, the standard manhole selected. Take the following conditions as an example: A liquid ammonia storage tank with a capacity of 50 cubic meters, made of Q345R material, with a design pressure of 2.16 MPa; it is classified as a Class III vessel. The design drawings specify that all pipe flanges should be made from Grade III forgings, while the manholes are to comply with the HG/T 21524 standard, which requires the use of Grade 16Mn forgings for such manholes. However, the audit requirements stipulate that the manhole flanges must be Grade III forgings. How should the design drawings be adjusted in this case? PS: Of course, grade II forged parts can also be used for the flanges; this is a requirement specified uniformly. We will not discuss the regulations regarding the grade of forged parts here. Please talk about the methods for handling the drawings
Please attach relevant screenshots of HG/T 21524 so that everyone can see how to proceed with the drawings appropriately Should the additional content be indicated in the remarks?
Will a grade II forged part be sufficient for this container? I couldn’t find where it states that grade III forgings should be used; please let me know~
We have indicated in the technical requirements that it should be changed to grade III forgings.
The overall technical requirements specified in the drawings will include a general requirement for the grade of the forgings; therefore, there is no need to repeat that requirement for manholes, right?
Considering the conditions of your equipment, using grade II forgings for the pipe flanges should be sufficient
Sure enough, they brought up this question. The standards do not require third-grade forgings; the company has established a uniform requirement of using third-grade forgings for all three types of containers.
It’s pointless; the discussion isn’t on point. I already said that from a standard perspective, both Grade II and Grade III are acceptable. The reviewer is demanding level III – what do you do? Please answer the required questions; this is not the place to discuss whether this manhole cover should be of grade 2 or grade 3
Do the overall technical requirements on the drawings establish a general requirement for the forging grade? What does that mean? I don’t understand.
The standards specify general conditions; if there are special requirements, they should be stated in the technical specifications.
Then, in the details column for the manhole, specify that the flanges should be made of grade III forgings, or change the material specified for the manhole flanges on the standard manhole drawings to grade III forgings