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Product Name: No-hub coupling for SML / EN 877 cast iron drainage pipe
Nominal sizes: DN 40 – DN 30
Shell / band: AISI 316 austenitic stainless steel (EN 10088-1)
Fasteners: A4-70 stainless bolts and nuts (EN ISO 3506-1 / -2)
Gasket: EPDM to EN 681-1; NBR on request (EPDM, NBR, FKM and TPE Compared)
Standard basis: EN877_2021
Construction: Cold-rolled, riveted, no weld seams
DINSEN supplies A4-70 bolts and nuts. A4 is the molybdenum-alloyed austenitic group (the 316 family), so the fasteners match the shell; 70 is the strength class, and it meets the minimum class the standard requires for stainless fasteners. Using one stainless family throughout also avoids a galvanic couple between a carbon steel bolt and a stainless band at the clamp lug — the usual place a coupling starts to rust.
Frequently asked questions
1. Is a no-hub coupling the same as a grip collar?
No. A no-hub coupling joins and seals two plain pipe ends. A grip collar is an add-on device that stops that sealed joint from pulling apart under end thrust. Grip collars do not seal; couplings do not provide axial restraint. Both are covered by EN 877, in clauses 4.12 and 4.13 respectively.
2. Why 316 rather than 304?
Both are permitted austenitic grades under EN 877 4.12.3. 316 adds molybdenum for markedly better resistance to pitting in chloride-bearing environments — coastal air, buried runs, de-icing salts, aggressive effluent. DINSEN supplies 316 as standard so one specification covers the demanding sites as well as the ordinary ones.
3. What does A4-70 mean?
A4 is the EN ISO 3506 group for molybdenum-alloyed austenitic stainless fasteners (the 316 family); 70 is the strength class. EN 877 requires stainless bolts and nuts of A2, A4 or C1 with a minimum strength class of 70, so A4-70 meets that requirement with fasteners matched to the 316 shell.
4. What gasket material is used?
EPDM to EN 681-1 for normal domestic and building effluent. NBR is available on request where oil, grease or specific fluids are present; special joints and applications may call for other elastomers.
Get a quotation
Specify DINSEN 316 no-hub couplings with A4-70 fasteners for your next EN 877 project. Send us the DN, quantity and certificate requirements and we will reply with the drawing, documentation list and price.
Email: info@dinsenpipe.com Web: www.dinsenclamps.com
