What the inspector looks for
Six ways a sanitary weld fails. How ours are built not to.
The acceptance criteria for a field-welded product line come down to three things: the joint is sound, it is smooth enough to clean, and the line drains. These are the flaws that break those rules, and what we do about each one.
FlawWhy it failsWhat we do
Sugared rootWhy it fails
No back purge, or a purge that quit early. Oxygen hits the inside of the joint and the root comes out gray and grainy, like burnt sugar. It traps residue and it rusts.
What we do
Every product-contact joint is argon back-purged, and the purge stays on until the root is as bright as the cap. No exceptions for “just one quick fitting.”
Pits, skips, no penetrationWhy it fails
A weld that did not fuse all the way through leaves a ledge or a crater on the inside where product collects. From the outside it can look fine.
What we do
Full-penetration passes at controlled heat. Any joint with a pit, crater, ridge or embedded material gets cut out and rewelded, the way 3-A practice calls for.
Heavy heat tintWhy it fails
Dark blue, purple or burnt discoloration means too much heat and a damaged chromium layer. It corrodes first and cleans worst.
What we do
Heat input kept low so tint stays in the light-straw range. Discoloration judged against the AWS D18.2 color levels, and reworked when it is over the line your plant allows.
Crevices at the jointWhy it fails
Tube ends that are out of round, off-square or misaligned leave a step inside the line. Product catches on the step, CIP flow skips over it.
What we do
Ends cut square, deburred and fit flush. Inside diameters matched so there is nothing to catch on, then checked again before the arc strikes.
Carbon contaminationWhy it fails
A wire brush or flap disc that touched mild steel leaves iron in the stainless. It shows up later as rust spots on a line that was never supposed to rust.
What we do
Stainless-only brushes, discs and tooling that never touch carbon steel. Clean filler, clean gloves, clean tube.
Lines that will not drainWhy it fails
A run that sags or pitches the wrong way holds solution after CIP. Standing liquid is where growth starts.
What we do
Lines pitched to drain points and supported so they stay that way. Checked with a level, the same way the inspector will check it.
3-A3-A Sanitary Standards and Accepted Practice 605 for welded product pipelines and CIP systems in dairy and food plants: inert back-up gas, complete penetration, drainable lines, welds inspected before polishing.
AWS D18.1The welding specification for austenitic stainless tube and pipe in sanitary (hygienic) service, written with 3-A. Its companion D18.2 is the color guide for acceptable discoloration inside the tube.
304 / 316LSanitary tube and Tri-Clamp ferrules, elbows, tees and valves in the alloy that matches what you have. 316L where acid, salt or chlorides are in play.