BML Cast Iron Pipe: Sizes, Standards and DN400 Supply

BML means Brückenentwässerung muffenlos — German for “bridge drainage, socketless”. DINSEN’s BML cast iron pipe is a jointless drainage system engineered for bridges, overpasses, tunnels, underpasses, car parks and buried property drainage — places where road salt mist and acidic exhaust destroy ordinary pipe.

Material, sizes and applications

DINSEN BML pipe is centrifugally cast in grey cast iron with flake graphite (min. EN-GJL-150), giving high compressive strength and low flow noise — both critical on bridge decks. Sizes run from DN 40 to DN 400 in 3 m lengths, supplied with matching BML fittings and stainless-steel couplings for fast, socket-free installation on site.

Standards and quality control

Every length is produced under ISO 9001 and tested to EN 877, ISO 6594 and DIN 19522. Internal coating: epoxy resin, ochre yellow, approx. 100–130 µm. External coating: approx. 40 µm plus 80 µm epoxy in accordance with DB 702; fittings are coated to ZTV-ING Sheet 87 (70 µm base + 80 µm top coat). Each batch is checked for wall thickness, coating thickness, hydrostatic tightness and ovality, with traceable test records shipped with the order.

DINSEN BML pipe DN400: ovality under control

Large diameter is where most suppliers fail. At DN400 the shell is thin relative to its diameter, and cooling distortion easily pushes a large diameter cast iron drainage pipe out of round — the usual result is coupling leaks, rework and slipped installation schedules. DINSEN controls DN400 ovality through tuned centrifugal casting parameters, controlled cooling and 100% roundness gauging before coating, so the pipe fits and seals the first time.

Not sure which system your project needs? Read What are SML, KML, TML and BML? Where to Apply Them? to compare all four socketless systems and their applications.