Airweld’s “Answer Man”, Victor Fuhrman, has 41 years of experience in the welding supply and compressed gas industry. An AWS CWI, Victor brings his expertise to our customers, providing solutions to make their jobs more efficient and productive while maintaining the highest quality.
Each month, Victor will select a question and answer it here. If he answers your question, you will receive an Airweld t-shirt! Send your question to: firstname.lastname@example.org
This month’s question comes from John B. of Queens. He asks:
Dear Answerman: In my business, we short arc MIG weld mild steel plate using .035” solid E70S-6 wire and C25 (75% Argon/25% CO2) gas. The welds are satisfactory but we are getting a tremendous amount of spatter requiring a lot of after weld clean up. What can we do to reduce the spatter?
Dear John: Spatter occurs when droplets of molten material are produced near the welding arc. This is usually the result of one or more of the following:
A. Currents are too high—check your wire feed speed and use the manufacturer’s spec sheet for suggested settings for the thickness of the plates you are welding.
B. Insufficient gas shielding—again the spec sheet will offer a suggested flow rate, usually somewhere between 25-35 SCFH (Standard Cubic Feet Per Hour) for short arc.
C. Torch to plate angle—increase the torch to plate angle, optimally between 5 and 15 degrees.
D. Contact tip to work distance—should be between ¼” and 3/8” depending on voltage.
Adjusting these parameters should solve your spatter problems. Thanks for asking!
This month’s question comes from Joseph M. of Islip. He asks:
Dear Answerman: I am silver brazing some copper tubing and need to purge and pressure test it. I thought I could use my oxygen tank to do this but a friend told me not to and to get nitrogen. Why?
Dear Joseph: Your friend is absolutely right! Pure oxygen should never be used for purging, pressure testing or any industrial application other than safe
oxy-fuel welding and cutting.
Oxygen behaves differently than air, compressed air, nitrogen and other inert gases. The air we breathe contains about 21% oxygen. Even a small increase in the oxygen level in the air – to just 24% – can create a dangerous situation where it becomes easier to start a fire, which will then burn hotter and more fiercely than in normal air. It is also very reactive. Pure oxygen, at high pressure – such as from a cylinder – can react violently with common materials, such as oil and grease. Other materials may catch fire spontaneously. Nearly all materials, including textiles, rubber and even metals, will burn vigorously in oxygen.
The right gas for purging and testing is nitrogen. It is inert and non-reactive. Your local Airweld branch has many sizes of nitrogen cylinders as well as regulators and hoses designed for pressure testing and purging. Thanks for asking!
This month’s question comes from Philip C. of Hauppauge. He asks:
Dear Answerman: The other day, I told one of my welders to reposition his ground clamp and he corrected me, saying that it is called a work clamp and not a ground clamp. I’ve been welding for thirty years and have always called this a ground clamp. Who is right?
Dear Philip: Actually, your welder is! Some of the expressions and slang used over the years in the welding industry are actually misused. In electrical terms, the word “ground” implies an electrical connection to the earth. In a welding circuit, the “ground” is actually the work connection. Welding manufacturers are now labeling this side of the connection on their power supplies as “work” and the clamps are work clamps. Give your welder an “A” for accuracy! Thanks for asking!
This month’s question comes from Joseph G. of Patchogue, New York. He asks,
Dear Answer Man: “What is the difference between E7014 and E7018?
Dear Joseph: While these two SMAW (Shielded Metal Arc or “stick”) electrodes have two properties in common, there is one property that makes a huge difference. They both start with “70” meaning a minimum tensile strength of 70,000 psi and they both have a “1” in the third position which means they can be used in all welding positions, flat, horizontal, vertical and overhead.
The fourth position here is the critical factor. This refers to the type of coating and welding polarity.
4 = Iron Powder Titania and AC or DC+ (Reverse Polarity)
8 = Low Hydrogen Potassium/Iron Powder and AC or DC+ (Reverse Polarity)
Where 7014 may be used for general purpose mild steel welding requiring 70,000 psi tensile strength, 7018 is used for structural steel and pipe applications requiring low hydrogen welds and meeting the AWS D1.1 Structural Steel Code. They were created to avoid hydrogen cracking on high strength steels and are moisture sensitive requiring storage in a rod oven between 250 and 300 degrees F. after the container is opened.
It is very important to know the difference. Thanks for asking!