preheat SA- 516 gr 70

[SAUL VASQUEZ T.]

 

Dear   all

 

We are   API 650 steel tanks with  steel ASTM  516 gr70 and our client requests that preheat to 70°C - 100°C is this correct? The API 650   code section 7-1 that says that  preheat at 10°C

thanks all

 

 

 

Cordial saludo

Kind regards

Saul Vasquez T.

--------------------------------

INGETANQUES LTDA

Cra 8B Nº 190-81 

Tel. 57 (1) 6794382  Fax 57 (1) 6723793

CEL. 320-3469363  y  316-5388051

Bogota D.C.    Colombia.  http://www.ingetanques.com/

 

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[nilesh]

Dear Saul,                We are also tank fabricator but we never do preheating.It is not the requirement as per API 650 if you have proper WPS with supporting PQR.We have welded 35mm A 516 GR 70 in our last project without preheating without anyproblem.   regds    Nilesh Parsekar,  Sr QC Co-ordinator  (Dip Mech,API 510,API 570,AWS-CWI,NDT LEVEL2)  Belleli Energy Spa  FUJAIRAH - UAE --- On Wed, 5/6/09, SAUL VASQUEZ T. <svas...@ingetanques.com> wrote:

[Narendra Gohil]

It depends on thickness.
What is the thickness?

Thanks & Regards
----------------------------
Narendra Gohil
Welding Engineer
QAFCO
Ph.00974-4228289(O)
Mo.00974-6044289
Email: ngo...@qafco.com.qa

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From:	"SAUL VASQUEZ T." <svas...@ingetanques.com>
To:	<material...@googlegroups.com>
Date:	07/05/2009 04:50
Subject:

	[MW:2114] preheat  SA- 516 gr 70

Sent by:	material...@googlegroups.com

---

[Hugo]

Hi Saul,

If you like, I can do some calculations (on the basis of the actual
base-material analysis) to find out:
1. The critical hardness, above which cracks can be expected.
2. The peak hardness which occurs in your HAZs
3. If crackrisc is present: how to influence the cooling rate between
800 and 500 degrees

Best regards,

Hugo

[Paresh Katvi]

Purpose of Pre heating are as follows:

 

1) To prevent Hydrogen Induced cracking- This risk is very high with CS material if thickness is more than 25 mm thick.

2) TO remove moisture and minor dust and dirt

3) It reduces fast cooling otheriwse it results in to unwanted unhealthy mircrostructure.

4) It some time help for distortion control.

 

Regards

[PB HEGDE]

Dear Saul

It is always good practice to preheat /preheat maint. CS ,LAS joint Generally recommended  i) 75C min for the joint 18 mm to 50 thk ii)  fOr 50 to 100mm thk –100 C min and above 100mm thk Joint It should be min 125C

(For CE  more than 4/4.5 , It is always recommended to preheat 125C irrespective of thk) All LAS should be preheated to min 100C

 

Improper preheating / absence of preheating of CS,LAS , causes higher weld/HAZ hardness (Hard strcture) resulting in cracks and distortion

 

Regards

 

Hegde P.B.

Head Welding Technology

ISGEC (India)