Welding required/Weldable fine grain steels, quenched and tempered (Steel grade PT610Q) ISO 9328-6 4

[tranmylinh]

Hi everyone,
Can you support me in welding requirements with thickness 32 mm in sphere tank following ASME VIII div 1 with teachnical specification: Material is Steel grade PT610Q (ISO 9328-6, Weldable fine grain steels quenched and tempered) Yield strength min. 490 Mpa, Tensile strength min 610 Mpa
+ Equivalent material in ASME IX (P.No and Gr.No)
+ Min. Preheat temperature and max interpass temperature
+ Post weld heat treatment ( minimum temp. and holding time)
+ Hardness testing requirement for PQR
Thank you & Best regards.

 

[weldstan]

I do not believe that this material can be used under ASME VIII, Div.1. If it is not listed in ASME II, Part D, it cannot be used.

 

[metengr]

It looks to me you are trying to follow ASME Section VIII, Div 1 rules for a pressure vessel sphere repair with the sphere having been built to another specification. This is not a problem.

The WPS can be qualified to Section IX using the actual material designation. Assignment of a P-No and Group number is not the correct approach.

I would use Section VIII, Div 1 Part UHT.

 

[tranmylinh]

Many thank to Mr metengr.
I'm trying to follow ASME Section VIII, Div 1. It is mandatory following to my contract. So I qualified WPS following to ASME section IX using the actual material designation. But when I looking for temp. and holding time for PWHT in Section VIII, Div 1 Part UHT, I can't find it in Table UHT-56 (Postweld Heat Treatment Requirements for Materials in Table UHT-23).
Can you support me in Postweld Heat Treatment Requirements for material designation (PT610Q)?
Thank you & Best regards.

 

[metengr]

This material may not require PWHT as with other UHT alloys because it may effect impact and strength properties of the bulk material and weld region. I would perform two weld coupons with and without PWHT and evaluate the effect of PWHT. Go back and review the material specification to determine the minimum tempering temperature of the PT610Q alloy. If you PWHT, I would remain at least 15 deg C below the original tempering temperature.

 

[tranmylinh]

Thanks Mr metengr,
OK, I will perform two weld coupons with and without PWHT following to your instruction. But when I looking for the minimum tempering temperature of the PT610Q in ISO 9328-6 and MILL'S CERTIFICATE, I can't find it. So, can you show me where to go look for heat treating specifications for this steel type?
Thank you for your time.

 

[metengr]

Your original statement mentioned quenched and tempered. What heat treatment was performed on this material? Was it just normalized?

 

[tranmylinh]

Dear Mr metengr,
The condition of supply was quenched and Tempred. Avegared Impact tested value of three test is about 247J.
Thanks.

 

[metengr]

The condition of supply was quenched and Tempred

The mill certificate should have stated the austenitizing temperature and tempering temperature.

 

[tranmylinh]

Dear Mr metengr,
I will require supplier sent it to me.
Thank you for your time.

 

[tranmylinh]

Dear Mr metengr,
I'm sorry to bother you, but when I reviewed MILL'S CERTIFICATE but it didn't state the austenitizing temperature and tempering temperature. And "Information to be supplied by the purchaser" prescribed by ISO 9328-6 which didn't require this information. So I don't now what is the next step. Could you spare a moment?
Thank you & Best regards.

 

[weldstan]

Could you provide the chemistry on the mill cert. With it an adequate PWHT, if required, could be provided.

 

[metengr]

Agree with weldstan. I was able to locate a copy of the ISO 9328-6 material specification

C 0.18%
Si 0.75
Mn <= 1.6
P <= 0.030
S <= 0.030
B <= 0.005
Cr <= 0.030
Cu <= 0.40
Mo <= 0.50
Nb<= 0.050
Ni <= 1.0
Ti <= 0.030

YS 490 N/mm[sup]2[/sup]
UTS 600 N/mm[sup]2[/sup]

This is a microalloy steel. It looks to me to be very similar to SA 517 Grade F.

The heat treatment for SA 517 is quench from 1650 deg F and temper at 1150 deg F minimum.

 

[weldstan]

Based on the above from metengr, with adequate preheat and interpass temperature controls, PWHT more than likely need not be performed.
You should be reviewing UCS-56 not UHT-56. Your material is low alloy steel, not high alloy steel.

 

[tranmylinh]

Dear Mr metengr and Mr weldstan,
When I received CERTIFICATE from supplier, I was able to locate a copy of the MILL'S CERTIFICATE:
C 0.10%
Si 0.22
Mn 1.52
P 0.11
S 0.03
Cr 0.13
Nb 0.02
Ni 0.01
V 0.06
Ceq 40
YS 598 N/mm2
UTS 694 N/mm2
EL 44%.
In my opinion,I think that it looks like to SA 724 Grade A, which pressure vessel plates,carbon-manganese-silicon steel, quenched and tempered, for welded pressure vessels with YS 485 N/mm2 and minimum UTS 620 N/mm2. The heat treatment for SA 724 Grade A is not applicable. Can you give me advice anymore?
Thank you for your time.

 

[weldstan]

While you could make a sound weld without PWHT, your hardness test requirements will govern the need for PWHT. What is the maximum hardness permitted?

 

[metengr]

tranmylinh;
The material you received is not even close to what you reported in your original material of PT610Q (ISO 9328-6, Weldable fine grain steels quenched and tempered).

The heat treatment for SA 724 Gr A is specified as a quench and temper, see excerpt below

5.1 All plates shall be quenched from a temperature in
the range from 1600 to 1700°F [870 to 925°C]. Grades A
and B shall then be tempered at not less than 1100°F
[595°C],

So, if you PWHT, you must remain below 1100 deg F, probably near 1050 deg F.

 

[weldstan]

For your PQR without PWHT to meet hardness requirements, I would recommend a 100C min preheat and a maximum interpass temp of 300C.

 

[tranmylinh]

Dear Mr metengr and Mr weldstan,
I will perform two weld coupons with and without PWHT following to your instruction(near 1050 deg F).In my contract, it's not require hardness requirements. And how to determine a maximum interpass temp? Could you spare a moment?
Thank you for your time.

 

[DekDee]

tranmylinh,
Please don't take this wrong but if you are involved in welding a spherical pressure vessel you really should have someone appropriately qualified involved.

Interpass temp is the measurement of temperature immediately before the next run is started.
If you weld vertically you would start at the bottom and finish at the top.
Before you start the next run measure the temp in the centre of the weld at the bottom.
This is your interpass temp.
Maximum Interpass is the highest interpass temperature recorded during welding of the test coupon,
Regards,
Shane