Tuesday, September 14, 2010

Re: [MW:6993] Regarding Preheat Temparature

Hi,
You didn;t mention the construction code.If the construction code is ASME Section-VIII,Div.1..there ia a recommendation for preheating as below.
But if the code is EN,there are some formulas to calculate the preheating as well as recommendations too.

NONMANDATORY APPENDIX R

PREHEATING

INTRODUCTION

Preheating may be employed during welding to assist

in completion of the welded joint. The need for and temperature

of preheat are dependent on a number of factors,

such as the chemical analysis, degree of restraint of the

parts being joined, elevated physical properties, and heavy

thicknesses. Mandatory rules for preheating are, therefore,

not given in this Division except as required in the footnotes

that provide for exemptions to postweld heat treatment in

Tables UCS-56 and UHA-32. Some practices used for

preheating are given below as a general guide for the

materials listed by P-Numbers in Section IX. It is cautioned

that the preheating temperatures listed below do not necessarily

insure satisfactory completion of the welded joint

and requirements for individual materials within the PNumber

listing may have preheating more or less restrictive

than this general guide. The procedure specification for the

material being welded specifies the minimum preheating

requirements under Section IX weld procedure qualification

requirements.

The heat of welding may assist in maintaining preheat

temperatures after the start of welding and for inspection

purposes, temperature checks can be made near the weld.

The method or extent of application of preheat is not therefore,

specifically given. Normally when materials of two

different P-Number groups are joined by welding, the preheat

used will be that of the material with the higher preheat

specified on the procedure specified on the procedure specification.

R-1 P-NO. 1 GROUP NOS. 1, 2, AND 3

(a) 175°F (79°C) for material which has both a specified

maximum carbon content in excess of 0.30% and a thickness

at the joint in excess of 1 in. (25 mm);

(b) 50°F (10°C) for all other materials in this P-Number.

R-2 P-NO. 3 GROUP NOS. 1, 2, AND 3

(a) 175°F (79°C) for material which has either a specified

minimum tensile strength in excess of 70,000 psi

(480 MPa) or a thickness at the joint in excess of 58 in.

(16 mm);

(b) 50°F (10°C) for all other materials in this P-Number.

597

R-3 P-NO. 4 GROUP NOS. 1 AND 2

(a) 250°F (121°C) for material which has either a specified

minimum tensile strength in excess of 60,000 psi

(410 MPa) or a thickness at the joint in excess of 12 in.

(13 mm);

(b) 50°F (10°C) for all other materials in this P-Number.

R-4 P-NOS. 5A AND 5B GROUP NO. 1

(a) 400°F (204°C) for material which has either a specified

minimum tensile strength in excess of 60,000 psi

(410 MPa), or has both a specified minimum chromium

content above 6.0% and a thickness at the joint in excess

of 12 in. (13 mm);

(b) 300°F (149°C) for all other materials in these PNumbers.

R-5 P-NO. 6 GROUP NOS. 1, 2, AND 3

400°F (204°C)

R-6 P-NO. 7 GROUP NOS. 1 AND 2

None

R-7 P-NO. 8 GROUP NOS. 1 AND 2

None

R-8 P-NO. 9 GROUPS

250°F (121°C) for P-No. 9A Group No. 1 materials

300°F (149°C) for P-No. 9B Group No. 1 materials

R-9 P-NO. 10 GROUP

175°F (79°C) for P-No. 10A Group No. 1 materials

250°F (121°C) for P-No. 10B Group No. 2 materials

175°F (79°C) for P-No. 10C Group No. 3 materials

250°F (121°C) for P-No. 10F Group No. 6 materials

 

For P-No. 10C Group No. 3 materials, preheat is neither

required nor prohibited, and consideration shall be given

to the limitation of interpass temperature for various thicknesses

to avoid detrimental effects on the mechanical properties

of heat treated material.

For P-No. 10D Group No. 4 and P-No. 10I Group No.

1 materials, 300°F (149°C) with interpass temperature

maintained between 350°F and 450°F (177°C and 232°C)

R-10 P-NO. 11 GROUP

(a) P-No. 11A Group

Group No. 1 — None (see Note)

Group No. 2 — Same as for P-No. 5 (see Note)

598

Group No. 3 — Same as for P-No. 5 (see Note)

Group No. 4 — 250°F (121°C)

(b) P-No. 11B Group

Group No. 1 — Same as for P-No. 3 (see Note)

Group No. 2 — Same as for P-No. 3 (see Note)

Group No. 3 — Same as for P-No. 3 (see Note)

Group No. 4 — Same as for P-No. 3 (see Note)

Group No. 5 — Same as for P-No. 3 (see Note)

Group No. 6 — Same as for P-No. 5 (see Note)

Group No. 7 — Same as for P-No. 5 (see Note)

NOTE: Consideration shall be given to the limitation of interpass temperature

for various thicknesses to avoid detrimental effects on the mechanical

properties of heat treated materials.

 

Thanks & Regards,

 

(Karthik)

Karthikeyan.S
QA/QC Manager
Getabec Energy Co.,Ltd.
379,Moo6,Soi8,Nikhomphatana,
Rayong-21180,
Thailand.
Phone: 0066 38 897035-8 (Off)
Fax: 0066 38 897034
Hand Phone: 0066 892512282


--- On Tue, 9/14/10, kamaleshwar sahu <kamaleshwar.sahu@beekaycorp.com> wrote:

From: kamaleshwar sahu <kamaleshwar.sahu@beekaycorp.com>
Subject: [MW:6991] Regarding Preheat Temparature
To: "Materials & welding group" <materials-welding@googlegroups.com>
Cc: kamsahu5@rediffmail.com
Date: Tuesday, September 14, 2010, 2:44 PM

Dear Sir,
           How we can calulate the Preheat Temparature of carbon steela.
 
Regards

Kamaleshwar Kumar Sahu
AGM(QA&I)
Cell: +91 97520 99054
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BEEKAY ENGINEERING CORPORATION
45/47, Industrial Estate, Bhilai (C.G.), INDIA
Tel: +91 788 4082240 (D) /4082200
Fax: +91 788 4082288/99
E-Mail: kamaleshwar.sahu@beekaycorp.com
Web: www.beekaycorp.com

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