Titanium And Stainless Steel Purges

Help customers achieve better pipe welds.

Damming system

Damming systems can purge as small as eight inches of internal pipe length.

Oxygen indicator

A good oxygen indicator can read below 50 ppm.

With the ever increasing use of stainless steel, titanium and other exotic materials in the metal working industry and the wide range of applications for chemical, nuclear, semi-conductor, petro-chemical, computer chip, pharmaceutical and food/dairy, the trend of high purity pipe welds will continue to grow—and is becoming the norm. Just ask any customers’ Q/A and Q/C departments. Welding supply distributors have just begun to scratch the surface of the sales potential to pipe welding customers in these industries.

In the past and too frequently still today, pipe weld purging related equipment was usually a home-made/in-house fabricated tool that welders built in order to address a particular concern or need. By introducing pipe weld purge dams, systems and related equipment, welding supply distributors can confidently recommend and rely on well thought-out designs and components that make a pipe fitter’s task easier and faster.

It comes down to asking your customer:  “Do you do any pipe or tube welding that involves stainless or titanium?” When a customer answers “Yes,” it’s now time to ask, “How do you currently purge the inside of these pipes? With Argon?”

Traditional Purging
Most welding industry articles point out that the traditional purging of pipe sizes ranging from ½-inch to 16-inches I.D. can take from 30 seconds on very small diameters to 25 minutes per lineal foot when purging with 20 CFH of Argon and a 5x to 6x volume change out of internal atmosphere. At that rate, the purge time when joining two 10-foot sections of pipe and purging from one end to the other, the welder’s “wait time” based on diameter is anywhere from 10 minutes to 8 hours and 20 minutes – for a single joint!

If your customer is damming and purging like the industry standard above and having welders wait until the purge is complete, you’d get their attention by asking: “Would you be interested if I cut your purge time to two to three minutes per joint, reduced the amount of Argon used, and  got you down to 50 ppm (parts per million) of oxygen or less before you weld?”

316L Stainless Coupons welded with an inert gas (Argon) purge at various rest oxygen values.Better than ‘Good Enough’
Besides the dams themselves, distributors can introduce other pipe weld/purge related items to increase the potential return on their sales call. Electrode grinders, pipe-alignment clamps and chains, high-heat-resistant aluminum tape, weld gauges, oxygen indicators, weld-backing tapes and low permeability purge hoses are common accessories. When a pipe welder is considering the use of internal damming systems, they don’t need to know only if they are re-usable. Other considerations must be made. Will there be any contamination from the “dam” material itself? Will it be easy to set up, then retrieve, once the weld is completed? Is it heat-resistant enough that it won’t burn up or burst near a weld? How will the Argon be delivered into the pipe? Are they using a heat-resistant, non-contaminating (halogen-free) tape? Can an oxygen indicator confirm that oxygen levels are low enough so that the welder knows when to proceed to weld?

With the right equipment in the customer’s hands, they can confidently and quickly purge their pipe joints to low oxygen levels and obtain high quality, non-contaminated welds. The old days of waiting around after calculating the 5x/6x purge-out volume timeframe, then purge a little longer, plus crossing your fingers, doesn’t cut it anymore. What’s the cost of a contaminated weld joint? The cost of cutting out the ruined segment, slipping in a new pipe, re-purging and now welding two joints is astronomical. The days of “it looks good enough” and “it should be good enough” isn’t “good enough” anymore. “Close, but no cigar” quite simply means, “Do it over again!”

Gases and Welding Distributors Association
Dave Dunbar Meet the Author
Dave Dunbar is in technical sales & marketing at Intercon Enterprises Inc., headquartered in Blaine, Washington, and on the Web at www.intercononline.com.