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Quality Control for non pressure applications

To provide a high quality pipe system, all Krah pipes have to pass the following minimum quality control requirements. In case of inside pressure applications, additional tests can be applied.

Additional to the own, in-house quality control a third-party, random inspection is recommended, to ensure a high quality product – the Krah Pipe System. The third-party quality control should take place twice a year. The company´s internal Quality Assurance department should provide a form for the checking. All samples checked shall be considered representative for the whole production. Raw material tests should be carried out before adding the product to the production cycle. Undamaged / non affected samples can be sold afterwards. Those tests made in Krah-Production Plants are exceeding the requirements of the international standards like DIN16961, ASTM F894, etc.

Krah Pipes laboratory for testsPhoto 1: Krah Pipes laboratory for tests

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Krah at Plastic Pipes 2017

CEO Alexander Krah at the last Plastic Pipes in 2015CEO Alexander Krah at the last Plastic Pipes in 2015

SOCIETY OF PLASTICS ENGINEERS INDIA, (SPE India), are pleased to announce Plastic Pipes 2017 International Conference to be held on 23rd and 24th November, 2017 at Hotel Leela, Mumbai and Krah Pipes will be there (again).

SPE India:
Society of Plastic Engineers India is a global leader in arranging Seminars, Technical Conferences and has always being successfully managing Seminars, and Technical Conferences, and have always managed to create a platform for Techno-Commercial discussions within the Plastics Industry. Being a recognized body, there is no doubt that participants will go back with a lot of information and knowledge after the event.

Current Scenario:
Worldwide the demand for plastic pipes is projected to grow > 5% per annum through 2019 to about 20 million KM from the current size of about 14 million KM. Construction applications make up the largest share of plastic pipes demand. Although construction spending is reportedly decelerating in China, the world’s largest plastic pipe market, plastic pipe demand in the country is still projected to rise by about 9% annually. Due to the ongoing efforts to expand the access to potable water and sanitation systems, the growth in plastic pipe demand is also expected to be robust in many developing countries. Technological advancements and improvements in polymer resins have caused an increase in share of plastic pipes in sectors including telecom, energy and industry.As far as India is concerned, plastic pipes is a well-established product since the first installation of PVC pipes in 1960s. The sector has grown substantially in last 5 decades and has reached the size of ~ 2.5 MMT. Their acceptance is increasing due to the long term performance, ease of installation and the awareness towards the ‘life cycle cost’ concept. Nationwide infrastructure development, rapidly increasing urbanization, Government’s focus on irrigation and the ‘make in India’ drive are some of the major factors facilitating the growth of plastic pipe industry in the country Alexander Krah will present the newest developments in large plastic pipe systems.

Alexander Krah

EL-Lene H112PC Superior Strength Polyethylene Black Compound for Pressure Pipes by SCG

Since ancient Roman aqueducts, water management has been continuously developed to become pipeline system and plastic appeared as the rising star material. With benefits of lightweight and flexibility, plastic was first used for pipes in the early 1950s, with continuous development of higher strength all along since then. Starting with PE63, the first generation of HDPE pipe material, followed by PE80 with an improvement of pressure resistance, the plastic pipe industry is now in the era of PE100, the third generation of HDPE pipe that was significantly developed in its key properties. In the present, PE100 is used to convey various types of flowing substances including water, gas (fluids), and slurries.

In 2014, SCG Chemical Co, Ltd. has successfully developed EL-Lene H112PC, an innovation with higher pressure with an MRS of 11.2 MPa. Our own developed polymerization process and special catalyst were selected to produce this advanced material, resulting in PE112 with no knee that perform beyond current conventional PE100.

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Bending and curving of Krah Pipes

The high flexibility is already very known for Krah-Pipes, and a basic reference for the bending is given by R=50 x DN/ID for long term and even R=25 x DN/ID for short term.

So technically these two cases have to be diveded, in long and short term examination. The long term is to reduce fittings (bends) and the shirt term aspect is during the installation e.G. using the S-sinking method in water applicaitons, relining. What is a easy way to make a detailed calculation, to be sure that the pipe will not fail. How to calculate the minimum bending radius for a Krah-Pipe with profiled wall structure, in helical style?

Short-term bending conditions, the welding was done  outside and now the pipe is moved into the trench DN/ID 1200 mmPhoto 1: Short-term bending conditions, the welding was done
outside and now the pipe is 
moved into the trench DN/ID 1200 mm

Rmin = α x DN [mm]

Rmin = minimum bend radius [mm]
α      = bend ratio [-]
DN/ID = Nominal pipe diameter, here inside pipe diameter [mm]

The minimum bend radius is defined as the smallest radius to which the pipe may be safely curved.

A maximum of total strain elongation should not exceed: 
ɛ =2,5 [%] (long term, 20°C) and 
ɛ =5,0 [%] (short term, 20°C).

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Water hammer and how PE pipes react

For designing a pressure pipeline all pressure load phases must be considered and in reference to the loading time be evaluated. Besides the test-pressure, the maximum operation pressure (MOP) and also the water hammer effect have to be considered and implemented in the static design! This procedure is valid for all pressure pipe materials and systems, but flexible pipe materials provide some advantages.

What is a water hammer? 
A water hammer is a pressure surge or wave caused when a fluid in motion is forced to stop or change direction suddenly. A water hammer commonly occurs when a valve closes suddenly at the end of a pipeline system, and a pressure wave propagates in the pipe. This pressure wave can cause major problems, from noise and vibration to pipe collapse. But it is possible to reduce the effects of the water hammer pulses with bypasses, expansion tanks, surge tanks, blowoff valves and other features. Rough calculations can be made e.g. by using the Zhukovsky equation, also known as Joukowsky equation.

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