[MW:567] Re: Tolerance for Dog leg

It seems to be a process piping with design code ASME 31.3.

If the fabrication/ construction code is ASME B 31.3, it also permits a miter bend upto 3° is acceptable (ref ASME B 31.2 Article 304.2.3).

In other words, a deviation/ deflection upto 3° can be considered as straight pipe & does not effect the design conditions (unless otherwise this tolerance is over ruled by designers with a strict requirement for maintaining a slope or aesthetic appearance is important than the allowable tolerance). Then do not look further for acceptance tolerance. Rectify the joint & make it straight.

best regards,

Sanjeevan 

Gulf Petrochemical Services, Muscat, Oman 

 

----- Original Message -----

From: Sankepalli R.S.Reddy

To: materials-welding@googlegroups.com

Sent: Tuesday, February 12, 2008 2:37 PM

Subject: [MW:565] Re: Tolerance for Dog leg

Here by attached the photo related to typical dog leg.

We are facing this problems in construction stage of plant piping. Allowing 3 Deg as tolerance appears to be more liberal and in lines like relief /blow down where slope of the line is  to be maintained process point of view. 

Thank you very much to all of you for your prompt reply.

 

Regards

 

Srs reddy

Saudi Aramco

 

 

 

 

 

On 2/11/08, Shyam Herur <herur.shyam@gmail.com> wrote:

Can you specify the pipe spec and what it is used for ? Since you are referring to "line pipe" I presume its the pipe covered in spec API 5L. However I did find an abstract which  goes" usually out of straightness of pipe usually follows a log normal distribution with diametre, and, as would be expected the larger the diametre of the pipe, the straighter is the pipe. API 5L allows  24mm in a 12m joint. usually it is possible to obtain pipe to 12mm in 12m. to reduce total cost over specification of straightness should be avoided".

 

also refer to API 5L for further details.

 

On 2/11/08, Sankepalli R.S.Reddy <sankepalli.rsreddy@gmail.com> wrote:

It is the out of straightness of line pipe. The out of straightness may be due to weld distortion at joint locations or due to improper fitup.

regards

 

On 2/11/08, Raghuram Bathula <raghurambathula@gmail.com> wrote:

Can you please explain the term Dog leg, i have no idea what it is?
Is it a term related to steel structure? type of stair case
arrangement?

On Feb 11, 7:39 pm, "Sankepalli R.S.Reddy"
<sankepalli.rsre...@gmail.com> wrote:
> *Dog leg or out of alignment of line pipe:*
> **
> Can any body gives permissible tolerance for Dog leg. Whether any standard
> is covering this tolerance.
>
> Thanks and regards
>
> S. Rama subba reddy
>
> Inspection Engineer
>
> Khursaniya Gas Project, KSA
>
> Bldg 7, Cu 1
>
> Ph no: 6770120

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