DIN/EN and ANSI/ASME Elbow Connections

Flanged and Plain Pipe End Configurations

PneuBend pocket-type cast elbows are proposed with flanged ends only. The five pipe-based families can be specified with straight pipe ends or with end flanges. The end arrangement is a distinct purchasing parameter and should never be inferred from the elbow body material or nominal size.

For a replacement, it is often useful to photograph the existing connections before removal. A dimensioned pipe interface can prevent misalignment and unplanned field work.

Steel DIN/EN Flanges and EN 1092-1

EN 1092-1 addresses steel flanges within its scope. The order should identify not just a vague “DIN flange” but the required standard, nominal size, PN designation, flange type, facing, bolt details and material. Older DIN drawings may use other conventions; check them rather than automatically converting the name.

A flange’s published designation is only one part of the assembly design. The body, welding, seals, gasket and service conditions determine whether the complete elbow can accept the intended pressure and temperature.

Aluminium Flanges and EN 1092-4

For cast aluminium pocket elbows, relevant aluminium-alloy flange requirements should be checked against EN 1092-4 where applicable. Integral cast flange geometry, alloy, manufacturing quality and pressure rating require a specific approved drawing. An EN 1092-1 steel-flange specification should not automatically be copied onto aluminium castings.

ASME B16.5 Flange Patterns

ASME B16.5 is widely used for specified metallic flanges and flanged fittings. Enquiries should state NPS, pressure class, flange facing, drilling and material, as well as any project-specific requirements. A Class 150 bolt pattern is not equivalent to claiming a Class 150 pressure-rated elbow without completing the engineering review.

DN Versus NPS and Pipe Outside Diameter

Nominal DN and NPS are descriptive series; they are not exact measurements of clear bore. A 2-inch nominal pipe does not have a 2-inch outside diameter. Pipe schedule, tube specification, lining and manufacturing tolerances also affect clear flow area.

Nominal Flange Class Versus Assembly Rating

The complete assembly may be limited by the housing, cast material, welds, liner, gasket, temperature or other factors. Obtain a model-specific operating envelope; do not derive it from a matching hole pattern or the highest rating of an isolated component.

Replacement Connection Checklists

Record both inlet and outlet connections separately. Include flange OD, bolt circle, hole quantity and diameter, face type, flange thickness, flange-to-center distance and pipe supports. If the installation has dissimilar ends, show that clearly on the drawing.

How to measure an elbow · Request a connection review.