Elbows to GOST 17375-2001 are type 3D — a radius of about 1.5 DN at 45, 60, 90 and 180 degrees, seamless, drawn from pipe over a mandrel. Tees to GOST 17376-2001 are equal and reducing; reducers to GOST 17378-2001 are concentric and eccentric; caps to GOST 17379-2001. Wall thickness follows the customer's pipe schedule, not the nominal figure in a price list.
We control what most often drifts out of tolerance: bend angle, section ovality, wall thinning in the bend and the geometry of the weld bevel. Marking carries DN, wall thickness and lot number, which ties the item to the mill certificate of the pipe it was made from. Long items ship in bundles with protected ends, and mixed sizes are loaded into one container to an agreed plan.