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FAQ - Part 1

A new section of our newsletter will from now on be the “Frequently asked questions”, shortly FAQ. In every issue we will answer some of the most asked questions we get from potential customers and interested parties about the Krah Technology.
Also feel free to send us some new ideas for our FAQ in he form below. We will try to publish as many as we can.


Which lifetime do Krah pipes promise?
Krah pipes are produced with high quality Polyethylene with live service times of more than 100 years, this meets the client’s requirements perfectly.
What is the stiffness of Krah pipes?
Any needed stiffnesses and stiffness class can be produced. Stiffnesses from SN2-SN16 acc. to ISO9969 are possible and also ring stiffnesses of SR2-SR164 acc. to DIN 16961. The wall structure is designed acc. to local requirements.
What is the delivery length of Krah pipes?
Usually Krah pipes are produced and delivered in a length of 6m, but in accordance to site conditions also any shorter length can be manufactured. Furthermore prefabricated pipe lengths of 18 m can be shipped to construction site to shorten the already short installation time.
Can Krah pipes resist inner pressure?
Yes, due to the tailormade design any Krah pipe provides a certain solid waterway wall-thickness for the requested inside pressure.
What is the dimension range?
Krah pipes can be produced in all inside diameters from DN/ID 400 until DN/ID 5000 mm, in steps of 100 mm. Other non-metric sizes are available on request.
How important is the eSDR in the Krah pipe production?
eSDR means “equivalent SDR (Standard Dimension Ratio)” and allows a simple comparison to axial extruded pipes with same stiffness. Often you find in tender text a SDR class mentioned, even if no pressure pipe is requested – only because of the related stiffness. A Krah pipe with e.g. eSDR11 provides exactly the same stiffness as an axial extruded pipe with SDR 11 – but with a much lower price!
How long can Krah pipes be stored?
The outside storage period depends from environmental conditions. At site we recommend 1 year max. storage time. At a factory under perfect conditions there is no limited storage time. Also check out our brochure “Storage and handling of Krah pipes”.
What about the bending angle?
Krah pipes can be bend in a radius of 50x pipe diameter. Due to the flexibility of Krah pipes, often additional fittings (bends, elbows) can be avoided.
How is the earthquake stability of Krah pipes?
Krah pipes jointed by E-fusion (or any other welding system) are flexibly designed and homogenously jointed. That provides the best possible safety against soil movements and earthquakes.
How do I connect Krah pipes? What do I need for it?
Usually Krah pipes get jointed by integrated E-Fusion, the socket is already homogenously formed at the pipe end, the other pipe end is equipped with a solid wall spigot. But also jointing by butt-fusion, extrusion welding or simply by rubber gasket is pssible. Your local Krah factory can provide you with all solutions.
How about Chemical resistance?
Polyethylene and Poly­pro­pylene are very resistant against many chemicals at certain temperatures. A bro­­­chure is for download avail­able under the Krah Pipes Downloads section or directly here “Chemical resistance of Krah pipes"