Training of installers according to EN 1591-4
Having to shut down operations due to a leak at a flange joint is every plant operator's nightmare.
In refineries, chemical and other plants, the causes of flange joint leakage failures have been investigated and investigated for a long time. The following table is the result of these investigations.
The above shows that up to 50% of the causes of leaks are due to incorrect installation. This is often due to stereotyped procedures based on experience with the installation of asbestos gaskets.
|Reasons for link failure
|Construction of the joint
|Installation of seals
The primary objective of the training according to EN 1591-4 is to give assembly workers a comprehensive understanding of how the different parts of a flange connection interact.
The basic qualification of EN 1591-4 contains 27 topics that can be divided into approximately 4 areas.
The aim is to elevate the work of a flange joint fitter to the level of a welder.
- Seal materials and their properties, leak classes, seal deformation during installation, etc.
- Fasteners, transmission of forces in the bolted joint, lubrication and its effect on tightening.
- Tightening procedures, records, protocols.
- Tightening tools, tightening methods, safety at work, leak detection.
The actual training and final exams include both theoretical and practical parts. The validity of the training certificate is 5 years. Extension is possible on the basis of an examination or by passing the whole training again, see. EN 1591-4 chapter 12.2.
The most common arguments we encounter against the usefulness of this training refer to years of experience and established practices.
"We don't have critical connections, we are not a chemical company or a refinery. We don't need training for our applications, our installers have always been able to handle it, we've been doing it the same way for years, we don't have leaks, etc."
From an installation perspective, it does not matter whether it is a critical flange connection or a common application. Even connections that have low parameters can be critical from an operational point of view.
The current state of standards for design and calculation of seals is based on standards that are more than 30 years old and in some respects refer to asbestos seals. However, the newly used sealants that have replaced asbestos have completely different properties and therefore different installation procedures and methods need to be applied to them.
It is common practice to give the fitter a gasket, a punch wrench and a hammer of the appropriate size. There can be no question of tightening torques in these cases.
Thanks to their experience, the installers will be able to cope in the vast majority of cases. The flange connection will therefore eventually pass the pressure test. But is it properly tightened so that it can operate smoothly even at the operating parameters of the equipment?
"How to tighten the flange connection correctly? Which gasket should I use with respect to the parameters of the joint? What tightening torque will I apply if I haven't got any? What will I lubricate the fastener with and what effect will that have on the overall tightening?"
We will be happy to answer these and similar questions in the assembly training.
What does certified training EN 1591-4 mean?
The procedure and the course of testing of flange fitters according to EN 1591-4 is approved by an independent body in accordance with EN ISO/IEC 17024:2013 conformity assessment. In the Czech Republic the independent approval body is ČIA (Czech Institute for Accreditation) and in Slovakia SNAS (Slovak National Accreditation Service).
The CIA or SNAS, as the certifying body, awards a mark with which the testing laboratory may stamp its own certificate issued to successful graduates of the training of installers according to EN 1591-4.
Our experience with this training according to ČSN EN 1591-4 was used to develop the methodology, procedures and evaluation criteria for testing external installers before the start of installation work (shutdown).
The importance of testing external fitters on their knowledge of basic flange joint assembly procedures provides operators with verification of their competence prior to assembly. Combined with the subsequent supervision of the actual assembly, it also increases the expected reliability of the flange connections.