Relation between pipe thickness and welding time

[tarekdata]

Dear Pipe Welding expert.

There are a strong and evident relation between pipe thickness and pipe welding time " assuming that pipe diameter is same " since the amount of metal deposit is exponentially proportional with pipe thickness.

Lets go Back to DIA -Inch welding definition, where We used to call Dia Inch = Pipe NPS X No of joint assuming that Pipe Schedule is STD or 40.

When higher Schedule or pipe thickness is exceeding STD or Sch-40, then we have to apply correction factor to up lift the actual figure of Piping Dia-inch that we have it , so the job will take the real volume of work.

You don't want to end up underestimating your work load by calculating the Dia-inch
" theoretical " as multiplication of pipe dia X No oj joint , and Ignoring the fact that some thick pipe " like XXS " joint , might be equal to 5 or 6 work volume of STD or Sch 40 pipe joint " for same diameter ".


I'm working on standard set of correction factor or Up lift factors enabling us to put and assign a fair correction factor for each pipe wall thickness.


please don't hesitate to share your best experience in this regard.

 

[BigInch]

Number of welding passes required for filling metal increases with the volume of the end bevel angle.

 

[SectionIX]

Appreciating that you could make this work using known factors, there are several other variables to consider:

++ Welding Process
++ Consumables (e.g. cellulosic/low hydrogen)
++ Welder skill
++ Consumable diameter
++ Welding conditions (sunny vs. -30C., slope vs. straight away)
++ Material grade (to an extent)
++ Welder fatigue
++ Etc...Etc..

Like Big Inch mentioned, joint design will also be a major consideration.

 

[racookpe1978]

TO start with, begin with a very accurate pipe prep diagram, then BEGIN with the algebra and geometry to calculate the weld volume: Root gap, ID of pipe, OD of pipe, prep angle, outside reinforcement. Throw in pi.

From those, you have the maximum (and minimum) weld volumes, assuming 100% weld and filler efficiency.

Assign a welder efficiency (GTAW will be more efficient in using filler than SMAW, for example).

Then throw in "time per cubic inch" of theoretical final weld volume for GTAW and SMAW, and FCAW if you use it.

Then throw in a "welder efficiency" margin (breaks, access, movement, getting in position, strain, etc.

Now, all of this is purely theoretical and estimates, so add a final "will cost/should cost" ratio.

Add tax, title and license fees.

 

[BigInch]

and stay under PWHT limits.

 

[weldstan]

Take a look at Design of Welded Structures by Blodgett. It simplifies some of the volume determinations.