carbon steel back strip

[eng ahmed]

Dear All

I had problem to weld pipe A53GrB using carbon steel back strip techniqe in RT interpretation,May i know the defects of welding the pipes using carbon steel back strip A109 type by GTAW process.

Best Regards

 

       

       Eng: Ahmed Gomaa
         QA/QC Engineer
                EGYPT
Email: Eng_ah...@yahoo.com
 Cell:   00201111350805

[chiluka venkatramulu]

Back strip will not be considered for RT interpretation.

CVR

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[c sridhar]

Mr. Ahmad,

Problems likely to be faced with back up strip at root are:

1. Lack of side wall fusion at the toes of strip  and pipe,

2. if the gap is more and if the tungsten size is less than 2.0 mm lack of blend

    (fusion & penetration)  of  filler wire on the  surface  of the strip,

3. If the welder is not alert, tungsten inclusion at places.

4. if the back up plate has any rust or  grease (oil) matter, porosity in the welds.

5. if the gap between the strip and pipe edges are more, voidness at places.

beyond the above the rest or insignificant.

sridhar.

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From: chiluka venkatramulu <ramulu...@gmail.com>
To: material...@googlegroups.com
Sent: Sunday, 5 August 2012 4:39 PM
Subject: Re: [MW:15026] carbon steel back strip

[syed moinul hasan]

Back strip is nothing to do with   any defects for RT interpretation, as long as welder is skilled & experienced.

[GOPU NAIR]

Please clarify whether the backing strip was left in place or removed after welding.  If the backing strip is left in place, there could be slag entrapment between the base metal and backing strip which will interfere with the interpretation of RT film. The alternative in such case is to have a tight fit joint and weld the root pass with GTAW. Good luck Gopu --- On Mon, 6/8/12, syed moinul hasan <mhs...@gmail.com> wrote:

[cbe swamym]

Dear All, Please Refe D1.1

 

4.30.3 RT.

If RT is used in lieu of the prescribed bend tests, the weld reinforcement need not to be ground or otherwise smoothed for inspection unless its surface irregularities or juncture with the base metal would cause objectionable weld discontinuities to be obscured in the radiograph. If the backing is removed for RT, the root shall be ground flush (see 5.24.4.1) with the base metal.  

The backing thickness shall be 1/4 in. [6 mm] min to 3/8 in. [10 mm] max; backing width shall be 3 in. [75 mm] min when not removed

for RT, otherwise 1 in. [25 mm] min. Figure 4.21—Test Plate for Unlimited Thickness—Welder Qualification (see 4.23.1)

6.11.1 Tubular Connection Requirements.

For CJP groove butt welds welded from one side without backing, the entire length of all completed tubular production welds shall be examined by either RT or UT. The acceptance criteria shall conform to 6.12.3 or 6.13.3 as applicable.  

6.17.3.2 Steel Backing.

When required by 5.10 or other provisions of the contract documents, steel backing shall be removed, and the surface shall be finished flush by grinding prior to RT. Grinding shall be as described in 5.24.4.1.

 

6.17.3.3 Reinforcement.

When weld reinforcement or backing, or both, is not removed, or wire IQI alternate placement is not used, steel shims which extend at least 1/8 in. [3 mm] beyond three sides of the required holetype IQI or wire IQI shall be placed under the hole-type IQI or wire IQI, so that the total thickness of steel between the hole-type IQI and the film is approximately equal to the average thickness of the weld measured through its reinforcement and backing.

 

Refer ASME VIII-A Table, UW-12

 

Thank & Best Regards,

 

M Veera SAMY- Bureau Veritas.

Coimbatore

 

 
 

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Date: Mon, 6 Aug 2012 12:22:53 +0800
From: gopuna...@yahoo.com
Subject: Re: [MW:15031] carbon steel back strip