SMS-13R Rd-Threaded Slotted Round Sanitary Union Nut (25–104 mm)

Six-Slot Round Collar and Rd Knuckle Threading

This SMS round union nut (SMS-13 / 13R SMS round nut series) is a cylindrical stainless steel collar nut with six radial perimeter slots for hook-spanner tightening. Its internal Rd knuckle thread and inward rear shoulder (bore A) capture the flat flange of an SMS-14 weld liner and compress it against an SMS-15 male part.

Material Options and Reference Source Scope

The primary catalog page specifies SS304 or SS316L stainless steel across a listed 25 mm to 104 mm nominal range. Secondary reference listings for 1"–4" 13R SMS round nuts (which exhibit a 304 vs 304L grade label discrepancy in their prose) are retained as comparative inch references.

Tabulated Dimensions Across Eight Rows (A, B, C, H)

On the SMS round nut drawing (mm), inner bore A, outer diameter B, thread C, and height H across the 8 rows are: 25 (A=32, B=51, Rd40×1/6", H=20), 32 (A=40, B=60, Rd48×1/6", H=21), 38 (A=48, B=74, Rd60×1/6", H=25), 51 (A=60, B=84, Rd70×1/6", H=26), 63.5 (A=73.5, B=100, Rd85×1/6", H=30), 76.1 (A=86, B=114, Rd98×1/6", H=32), 101.6 (A=115, B=154, Rd132×1/6", H=35), and 101.6 (Min) (A=113, B=140, Rd125×1/4", H=32).

101.6 mm Dual Variants and Selection Checks

When ordering for 4" (101.6 / 104 mm) SMS lines, confirm whether your mating SMS-15 male part uses the larger '101.6' thread (Rd132×1/6", nut OD 154 mm) or the compact '101.6 (Min)' thread.