Choose between ASME or MSS standards. 1

[Piline]

Hello everybody,

I am busy setting up catalogs (dimensions) for 3D piping software. I once read an article about the relationship between ASME and MSS standards “MSS standards should complement the guidelines of the ASME documents”. In my specific case it is ASME B16.9 and MSS SP-75. There is a difference in the ranges but the dimensions are the same. Materials have a small overlap (A234 & A420). I have doubts about choosing the right standard. Here are some highlights of the standards;

ASME B16.9 Factory-made wrought buttwelding fittings
1 SCOPE
1.1 General
This Standard covers overall dimensions, tolerances, ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1 ⁄ 2 through NPS 48 (DN 15 through DN 1200).

5 MATERIAL
Wrought fittings covered by this Standard shall be in accordance with ASTM A234, A403, A420, A815, B361, B363, B366, or the corresponding standard listed in Section II of the ASME Boiler and Pressure Vessel Code.

MSS SP-75 Specification for high-test, wrought, butt-welding fittings
1 SCOPE
1.2 This Standard Practice governs dimensions, tolerances, ratings, testing, materials, chemical and tensile properties, heat treatment, notch toughness properties, manufacture and marking for high-test,butt-welding fittings NPS 60 and smaller. Dimensional requirements for NPS 14 and smaller are provided by reference to ASME B16.9.

6. MATERIALS
6.1 The steel shall be fully killed and made using recognized melting practices to provide intended heat-treat response and notch-toughness properties.
Steel shall be made by open hearth, basic oxygen, or electric furnace process and shall be suitable for field welding to other fittings, flanges, and pipe manufactured under the following specifications: ASTM A53, A105, A106, A234, A381, A420, A694, or the corresponding ASME standard, or API 5L, and MSS SP-44.

12. FITTING DIMENSIONS
12.l One of the principles of this Standard Practice is the maintenance of a fixed position for the welding ends with reference to the center line of the fittings or the overall dimensions, as the case may be.
Dimensional standards for fittings NPS 16 and larger are shown in Tables 3 through 9. Dimensional standards and tolerances for NPS 14 and smaller sizes are contained in ASME B16.9.

ASTM A234
1. Scope
1.1 This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction covered by the latest revision of ASME B16.9, B16.11, B16.28, MSS SP-79, and MSS SP-95. These fittings are for use in pressure piping and in pressure vessel fabrication for service at moderate and elevated temperatures.

ASTM A420
1. Scope
1.1 This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction, covered by the latest revision of ASME B16.9, ASME B16.11, MSS-SP-79, and MSS SP-95. These fittings are for use in pressure piping and pressure vessel service at low temperatures.

In my case, filling database with dimensions, the following questions;
1. Which standard should I refer to?
2. Do the Codes (ASME B31.x or EN13480) matter in this case?
3. If it is the ASME standard, in which case I refer to the MSS standard?

The database is currently not yet filled with a material type. A significant detail is that the ASTM standards (A234 & A420) do not refer to the MSS SP-75, but to the ASME B16.9.

For the range 1/2” - 24” I tend to refer to the ASME B16.9, is that correct?

Thanks in advance

 

[1503-44]

Did you forget about MSS SP-44 and ASTM A-105, or do flanges come later?

"Complementary" means use together; that's not either/or.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[GBTorpenhow]

For catalog dimensions for butt weld fittings you should go to ASME B16.9 and MSS SP-75. A234 and A420 are material standards only. MSS SP-75 is both - for high yield fittings only.

A234 and A420 as far as I recall do not include high yield grades which is why they don't reference MSS SP-75. See ASTM A860 for high yield buttwelding fittings, this should reference MSS SP-75 for dimensions.

I recommend for grades covered in A234, A420, A403 to reference B16.9, for high yield fittings reference MSS SP-75.

 

[1503-44]

Complementary - both together, A, B and A+B, where each apply separately, or both apply.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[Krausen]

B16.9 is a dimensional standard you will need for buttweld fittings. A234, A420, & MSS SP75 are material standards for buttweld fittings (among others) that govern your metallurgy. Use B16.9 for your dimensions & the correct material spec depending on the material you need.

 

[GD2]

Piline,
MSS-SP-75 is more restrictive. The standard is made for High Pressure Transmission pipeline and distribution system, usually high yield strength materials.
As soon as one selects the Standard, it will kick in additional tests and control on the material, such as burst test, notch-toughness and CE.
If you use the same material say in ASME B31.3, these tests and controls are not required.
On dimension, NPS 14 and smaller, it follows ASME B16.9
NPS 16 and larger, the standard has its own dimensional tables.

GDD
Canada

 

[Piline]

Thanks for the input,

First of all, I'm not completely familiar with the materials yet, but when you read the scopes of both standards, I intuitively felt that it had to be the ASME standard. Your comments confirmed my suspicion. I need to review a "dimensional" catalog that references the MSS SP-75. i.m.o. is this not correct because no requirements are specified yet. I can therefore suffice with the ASME standard as a starting point. Now it's only about the elbows, but soon the other fittings and flanges will be added. As soon as there are additional requirements, it is easier for me to make a switch from the ASME to the MSS.

ps. the catalogs are from Autodesk Plant 3D software but you have to correct a lot of them.

Thanks for all valuable comments.

 

[XL83NL]

Based on the questions raised in the OP, I've decided not to waste an hour of my time to provide an internet-free eng-tips consulted college in piping engineering, codes and standarrd; instead, I leave it with this.

Huub
- You never get what you expect, you only get what you inspect.