Calculation for root gap according to tihckness of pipe

[abhishek ojha]

Dear Expert, Kindly guide me how to calculate root gap according tihckness of pipe of different /same dia.(different tickness but same dia) Thanks & Regards,   Abhishek Ojha  Engineer- Construction

[Dinesh Somwanshi]

dear abhishek ,

Root gap you can refer from an wps .Generally as per standard the root gap is 3-4 mm max to have full penetration at joint. 

if it is different thickness so you has to go for internal bevelling near id so your thickness get matched .

regards

dinesh

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[Fitria Rahman]

please find out the welding procedure to get the answer. the specification includes the sketch of joint that show the size of the root gap and root face. Normally, 1-2 mm is more advisable.

If thickness of pipe is different, trimming is required. Find out in design code that you're referring to.

2011/7/22 abhishek ojha <abhishe...@yahoo.co.in>

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[dhiraj tiwari]

Could anybody just give me the formula for calculating the root gap while welding ?

[Mohd Siraj]

Root gap is  not depend on pipe size or thickness,indeed it is based on process to be used for welding.

GTAW-4-5mm

SAMW-3.5-4.5mm

SAW-1.5-2.5mm

[munee...@gmail.com]

Hi,

Refer 328.4.3 of ASME B 31.3 and fig 328.4.2 and same as B 31.3 also refer B16.25.

Thanks.

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Regards,

Mohamed Muneeb Mahaboob

CSWIP 3.2-89247/2 

IRCA-9001:2015 LA

ASNT-NDT-L2-RTFI-RT-UT-MT-PT.

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''If you know any art by any means then SCULPT IT - no matter how cheap or useless it is - JUST SCULPT IT, you will never know when experts will be on demand'' 

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[GENE MATSKO]

Root gap is not dependent on pipe size or thickness. For the GTAW process the root gap is generally listed as 1/8 of an inch plus or minus 1/32 inch. in the WPS. For stainless steel open butt welding with the GTAW process this root gap will be increased due to shrinkage issues. Remember, one could run a PQR using 1/32 in. open root or 1/16 in. open root or a 5/32 inch open root and it will pass. The general standard in the U.S is 1/8 in. plus or minus 1/32 inch. Most good GTAW welders can handle this root gap. 

Gene Matsko

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[Hisham Al-Metwally]

Dear Mohd,

There is nothing mentioned in ASME IX or B31.3 codes regarding the gap calculation. It completely depends on the WPS/PQR.

On Tue, Jan 1, 2019 at 2:38 PM Mohd Siraj <mohd...@gmail.com> wrote:

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Root gap is  not depend on pipe size or thickness,indeed it is based on process to be used for welding.

GTAW-4-5mm

SAMW-3.5-4.5mm

SAW-1.5-2.5mm

On Friday, July 22, 2011 at 2:17:46 PM UTC+3, abhishek ojha wrote:

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Thanks & Regards

Hisham Al. Mohammad

Welding Engineer & QA/QC Engineer

Mob: +971 56 433 7326 & +971 52 667 9935

[munee...@gmail.com]

Agree its a process and also regardless of procedures, a skilled welder can handle any root gaps but if it is not acceptable, he will not proceed.

Thanks.

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Regards,

Mohamed Muneeb Mahaboob

CSWIP 3.2-89247/2 

IRCA-9001:2015 LA

ASNT-NDT-L2-RTFI-RT-UT-MT-PT.

SAP#:70021650 APs:JAPID, QCS & QCI.

E munee...@gmail.com M +91-636-955-7189

''If you know any art by any means then SCULPT IT - no matter how cheap or useless it is - JUST SCULPT IT, you will never know when experts will be on demand'' 

[munee...@gmail.com]

Dear, 

cherry picking section IX, which is never mentioned?

nothing mentioned? but it directs and also clears for branch connections.

More over its just a broad understanding of joint designs as per ASME B 31.3, 1 and B 16.25, which states in alignment (a) Circumferential Welds (1) Inside surfaces of components at ends to be joined in girth or miter groove welds shall be aligned within the dimensional limits in the WPS and the engineering design.

A broad understanding with easy go, but still its a designer / welding engineers choice.

Thanks.

---

Regards,

Mohamed Muneeb Mahaboob

CSWIP 3.2-89247/2 

IRCA-9001:2015 LA

ASNT-NDT-L2-RTFI-RT-UT-MT-PT.

SAP#:70021650 APs:JAPID, QCS & QCI.

E munee...@gmail.com M +91-636-955-7189

''If you know any art by any means then SCULPT IT - no matter how cheap or useless it is - JUST SCULPT IT, you will never know when experts will be on demand'' 

[GENE MATSKO]

asme section 9 is also called section IX. it is the qualification for welders for pressure pipe and vessels. it covers both brazing and welding and it is pretty much the industry standard for testing of pipe welders for power plants and such.

WPS does not provide dimensional allowances for joint design.

Piping codes address engineering design.

ASME B31.1, B31.3. are the primary piping codes and give the dimensional tolerances for 

piping alignment. 

Generally your Construction Procedures should address all code requirements with adequate

figures, (drawings). The Construction Procedures are taken directly from the applicable code and should reference the page, drawings etc. that they were taken from. Shop and field fabrication and welding of pipe will be delineated in a Pipe / Welding Fabrication Procedure 

These Construction Procedures are generally approved by QC before the start of construction. These Construction Procedures are provided to the field engineers, inspectors,

foreman etc who need them to do their work. These Construction Procedures are much easier

to use than the code book they were taken from.

Gene Matsko