Bolting material for API 12D

[Umar107]

Can we use bolting materials other than those listed in API 12D specification? Auditor has raised the concern for using material other than those listed in clause 4.9. However it is clearly mentioned in 4.1 and 4.9 that we can use alternate material with better or equal properties.

 

[r6155]

"The auditor has expressed concern about the use of material other than those listed in clause 4.9."
Ask him why.
What is the material you select?, why?

Regards

 

[GD2]

COVID107,
Give us more details. What is the material in API 12D and what is the alternate material you have proposed and why?

GDD
Canada

 

[Umar107]

Bolting material in API 12D is A307 Gr.A or B. We have used A193 B7 (in design documents) due to easy availability and superior strength.Production dept. seek approval for use of Iso 898-1 due to urgency of project (as these bolts were available in stores).Design dep. allowed the use of these fasteners based on higher strength.
Auditor says you can't use materials other than listed in API 12D (i.e. A307 A or B).But it is clearly written in 4.9 that other materials can be used.

 

[GD2]

Covid107,
A307 bolting are of low strength as opposed to high strength A193 B7.
If you are using flange combination of ASME B16.1, ASME B16.24, MSS-SP-42 or MSS-SP-51, most codes will prohibit to use A193 B7. The reason being by using high strength bolting material for low strength flanges, you are most likely to cause trouble in bending/breaking the flange leading to leakage by uncontrolled torqueing of the bolts.

What's your flange material combination?

GDD
Canada

 

[Umar107]

API 12D section 4.1 clearly states that alternate material shall have equal or superior mechanical strength. Flange material is A516 70.

 

[GD2]

Covid107,
A307 Gr A is generally used for general bolting application. A307 B is usually used for cast iron flanges.
I would guess API 12D specifies A307 for general bolting.

In your case, the flanges are made of A516 Gr 70.

You can use A193 B7 for A516 Gr. 70 flanges.

I guess there is an Appendix A in the standard that talks about minimum tensile strength requirement of 80 ksi for bolts 1/2" dia upto 1-1/2" long. Again A193 B7 is adequate for this as well.

Unfortunately, I don't have a copy of API 12D. Check if A516 GR 70 is acceptable flange standard in API 12D. Typically A516 Gr 70 is used for slip-on, blind, reducing flange and spectacle blinds.

Almost every standard/codes gives you flexibility of using alternate materials as long as it meets the code's/standard's qualification requirement. Check what exactly the paras 4.1 and 4.9 reads.


GDD
Canada

 

[r6155]

API 12K 2019 Specification for Shop-welded Tanks for Storage of Production Liquids

B.13.2 Materials
Unless specified otherwise by the purchaser, all carbon steel bolts for walkways, stairways, ladders, and flange
bolting shall conform to ASTM A307, A193M/A193, ASTM A325, or ASTM A325M. Nuts shall comply with
ASTM A563

B.13.5 Bolting Procedure
Bolt hole dimension and bolting installation tension requirements shall follow the AISC Steel Construction Manual


API 12D 2017 Specification for Field-welded Tanks for Storage of Production Liquids

4.9 Bolting
4.9.1 Bolting shall conform to ASTM A307, Grade A or B.
4.9.2 Nuts, when used with bolting, shall conform to ASTM A563.
4.9.3 Unless otherwise specified on the purchase order, black finish bolts and nuts shall be furnished.
4.9.4 When specified to be galvanized, bolts and nuts shall be zinc coated in accordance with
ASTM A123/A123M.
4.9.5 Alternative materials and/or finish, conforming to recognized standards for bolting, may be
furnished by agreement between the purchaser and the manufacturer

AISC is not mentioned like B.13.5 in API 12K

Hope the next edition of API 12D will be revised as API 12F.

Good engineering practices are: torque value and lubrication material for bolt installation will be shown on drawings.

Regards

 

[GD2]

Covid107,
You have your answer in 4.9.5. Just make sure that you have the Owners agreement.
Second, You need to challenge the Auditor. Tell them that A193 B7 is allowed by rule 4.9.5 of Specification 12D. If they want to challenge 4.9.5 they can write to API. There is a procedure and form they need to submit.

Specifications/Standards/ Codes are written by committees with experienced members from different backgrounds.

I am not sure of the Auditors experience, but if you challenge their point of view, they should justify their decision.

GDD
Canada