Large diameter HDPE pipes

How do we manufacture our HDPE pipes?

We manufacture our PPA&KRAH pipes and fittings using helical extrusion technology, in accordance with the guidelines of DIN 16961 “Thermoplastic pipes and fittings with profiled outer and smooth inner surfaces”.

The combination of the translational movement of the extruder head, with the rotational movement of the mold, generates a helix of material that covers the surface of the mold (the steel mold on which the pipe is manufactured defines the internal diameter of the PPA&KRAH pipes)

The helical extrusion system on a mold allows the extrusion of solid walls of any thickness, with the possibility of reinforcing them by means of internal or external lightened sections.

“All pipes and accessories incorporate socket-spigot ends, with the possibility of mounting other ends on demand (flanged, flat and combinations)”

The socket is formed in the manufacturing process on the mold. The tapered spigot end is machined in a post-extrusion step after the pipe has cooled.

“The pipes are manufactured in one piece”

The integrated co-extrusion system, together with the main extruder, allows the extrusion of homogeneous walls of black PE100 and yellow PE100, giving the possibility of improving visibility inside the pipes. Co-extrusion also allows the homogeneous extrusion of PE walls with internal linings of electro-conductive material.

Types of HDPE pipes available

The PPA&KRAH piping system has one of its main advantages in the possibility of manufacturing the optimal solution from the structural and therefore economic point of view, for each particular case

The optimization of the pipe is achieved by manufacturing the required solid thicknesses, combined with helical structured reinforcements (lightened sections), which increase rigidity while keeping the internal diameter unchanged.

The combination of solid thicknesses and structured profiles is studied for each particular working condition, providing the pipe wall with the necessary balance to withstand the loads to which it will be subjected during transport, storage, installation and operation.

The basic typologies of the walls of the pipes, accessories and special pieces are grouped into the 4 families that we describe below:

Solid profile HDPE pipes (VW)

Solid profile HDPE pipes (VW) have the following main characteristics:

• Solid walls without lightened section with thicknesses from 5mm to 300mm. Mainly used for the manufacture of accessories and special parts.
• Possibility of manufacturing the required thickness without having to adapt to standard thicknesses.
• Possibility of manufacturing VW walls with variable thicknesses, especially suitable for storage tanks.
• Possibility of manufacturing bars for machining special parts without welding.

HDPE pipes with helical corrugated profile (PR)

Helical corrugated profile (PR) HDPE pipes have the following main characteristics:

• Solid walls of variable thickness (from 5 mm to 100 mm) and an external helical reinforcement of variable diameter, pitch and thickness.
• They constitute the lightest range of pipes, with a smooth inner surface and a helical corrugated outer surface.
• With main application in pipes with wall moment of inertia ranges from 1000mm4/mm to 25,000mm4/mm.
• The moment of inertia of the pipe wall is directly proportional to its stiffnes.
• The solid wall thickness to be incorporated in the profile will meet the requirements of the structural calculations of the pipe.

HDPE pipes with internal structured profile (SQ)

HDPE pipes with internal structured profile (SQ) have the following main characteristics:

• Lower wall (interior of the pipe) and another upper wall (exterior of the pipe) of variable thickness between 5 and 100 mm reinforced with continuous interior lightened sections, generating “sandwich” type profiles.
• The square-shaped continuous lightened structures can have different diameters and have various heights (SQ1, SQ2, etc.)
• These profiles provide greater inertia than the PR profiles with a range from 15,000 mm4/mm to 120,000 mm4/mm. They are therefore the most suitable for pipes that require very high stiffness and especially for large diameter pipes.
• SQ pipe and fittings have smooth inside and outside surfaces.

HDPE pipes with special profiles (SP)

HDPE pipes with special profiles (SP) have the following main characteristics:

• One or more SQ profiles reinforced with a PR profile. Used in those cases in which special rigidities are required.
• The selection of the appropriate pipe profile is based on the structural calculation carried out according to the ATV-A127 standard.
• The manufacturing range of pipes, accessories and special parts covers from an internal diameter of 800mm to an internal diameter of 4000mm.
• The interior yellow colour can be considered in all pipes and accessories in order to facilitate their inspection once installed.
• The standard (effective) length of the pipes is 6 m. Shorter lengths available on request.
• Possibility of supplying factory-tested and welded pipes up to 12 m in length. 12m pipe supply speeds up installation.

Examples of applications for onshore HDPE Pipes

Fittings and special parts for HDPE pipes

PPA&KRAH has a complete range of accessories and special pieces tailored to each project, both for land applications (PPA KPS) and for marine applications (PPA OUTFALL).

With the PPA&KRAH piping system, a homogeneous and watertight piping network is possible for any type of installation:

• Elbows/Curves for any angle and radius of curvature.
• Tees with reinforcements in the graft area.
• Concentric and eccentric reductions.
• Welded leads.
• Flange holders / fixed flanges with loose flange in GRP or metal. Manufactured in one piece with a male or female end.
• Diffusers.
• Special pieces.

“Homogeneous and watertight pipes for any type of installation”