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Solutions for a 'zero-carbon' industry. SPETECH® LAB in the search for new process sealing systems

Janusz Zajączek, Manager of SPETECH® Testing Laboratory

 

Today's demands of energy transition and 'zero-carbon' have posed new challenges to the manufacturers of industrial systems, as well as the manufacturers of their components. Process equipment, heat exchangers, fittings, connectors, piping - these are just some of the components subject to new standards and regulations, the requirements of which aim to reduce Fugitive Emissions. This has forced both designers and research centers to work on new designs and sealing materials and to test them for their tightness.

SPETECH® Laboratory

The SPETECH® Laboratory of Sealing Materials was established in 1996 as a research unit and  its purpose is the testing of seals and fittings. The laboratory is mainly engaged in the testing of seals for flange joints and gland seals. The examinations mainly involve tests to measure tightness/leakage levels and to determine the mechanical properties of seals. As a result of flat gasket testing, flange joint designers are provided with values of design factors adequate for the calculation standard and, e.g. characteristics of the variation in gasket thickness. These data make it possible to correctly design the flange joint analytically or by Finite Element Methods (FEA).

Photo 1 View of the test rigs in the SPETECH® Laboratory

 

Testing and certification of valves, gates, cocks, butterfly valves is another component of the laboratory's activities. Newly designed and manufactured fittings are more and more often required to be certified to meet stringent tightness conditions.
The laboratory employs qualified engineers with many years of experience in operations related to sealing techniques and scientific research. They are specialists in the fields of mechanics, design, analysis of physical parameters, IT and programming. Their expertise guarantees that not only are the tests conducted correctly and the results interpreted accurately , but also the ability to provide technical support to customers. Support may include technical analyses, expert opinions, suggestions for possible design changes to seals or testing components.
Our laboratory is certificated by TÜV Rheinland Technical Inspection Office. All procedures used are included in the quality system based on the EN ISO/IEC 17025 standard.

Range of testing

The test rigs  available in the laboratory can be divided into different groups. The first division is the testing rigs for flat gaskets according to European (EN, ISO) standards and American (ASME) standards. A different group includes leak testing rigs and mechanical property testing rigs. The valve test stand is based on the valves themselves - the valve being the test station. With adequate instrumentation, it constitutes a fully equipped measuring station.
A unique feature of our test rigs is that they were designed and programmed by our employees. This makes it possible for us to adapt any testing procedure in which they operate to meet the specific conditions of the test being conducted (if simulating test in any specific working conditions and relevant gasket data for designing purpose are necessary). 

Testing of flat gaskets

The laboratory has three testing rigs built based on the requirements of PN-EN 13555. The first one “POWERPRESS#1” is intended for determining the mechanical properties of gaskets at ambient and elevated temperatures: maximum gasket surface pressure – Qsmax, modulus of elasticity – EG, creep and relaxation factor – PQR. On this stand the temperature can reach up to 850oC. The gasket friction factor(μG) is determined on a specially accurate module for the station. The temperature of this test can be raised to 500oC.
At this station it is also possible to determine calculation coefficients m and y used in ASME Code s. VIII for calculating the tension on bolts in a flange joint.

The second station “POWERPRESS#2” is used to measure leakage parameters at ambient temperature and in relation to tightness classes; minimum gasket surface pressure during loading / installation - Qmin(L); minimum gasket surface pressure during unloading / operation - Qsmin(L). Both above rigs are capable to test gaskets sized DN40 PN40 acc. EN1514 standard.

Third rig POWERPRESS#3+ is a combination of the capabilities of rigs #1 and #2. Additionally, it makes it possible to determine the leakage parameters of gaskets at elevated temperatures (up to 500oC) and testing of gaskets with NPS 4 Class 300 dimensions.

  

Photo 2 POWERPRESS#3+ test rig                                                                      Photo 3 Valve prepared for the heating process

 

The laboratory can determine relaxation and creep rates, compressibility and elastic recovery according to ASME standards, and determine resistance and resistivity according to the European standard.

Certification of valves

The testing and certification of valves completely fits into the concept of ensuring zero-emissions. It is estimated that valves and their connections emit about 90% of the emissions of various substances, including those harmful to the environment.  The stringent requirements of EN ISO 15848-1 for acceptable emission levels pose challenges to both valve designers and seal manufacturers.
In order for the valve to be seen on the market as a low-emission, it must pass a certification pro-cess. Both shut-off and control valves can be tested. They are subjected to endurance open/close cycles and temperature cycles. The medium used in this process is mostly helium, but methane can also be used. The valve manufacturer, based on the provisions of the standard, de-termines in which endurance class and temperature class the valve is to be tested. The range of temperatures in which testing is carried out is very wide: from -196oC to 400oC. Based on the suc-cessful test results, the valve is classified into one of the tightness classes listed in the standard and a certificate is issued for it. It contains, first of all, information about the A, B or C tightness class of the valve, as well as information regarding the mechanical and temperature class which has been met.
 

Technical consulting - a case study: NPS 6" ball shut-off valve with pneumatic actuator

The testing of fittings in many cases involves solving various technical problems. This is primarily due to the fact that manufacturers designate new valves for testing, i.e. those that are not on the market yet and have not yet been tested for tightness. The test results of such valves, as well as the testing routine itself, are burdened with many uncertainties about the behavior of the object which is being subjected to testing. This is where the expertise and experience of the laboratory staff comes in handy.
One such difficult case was the pneumatically actuated NPS 6'' shut-off ball valve. Testing was conducted according to EN ISO 15848-1 for endurance class CO1, 150 bar at 200oC and 200 bar at ambient temperature. During the execution of the last 5 cycles, out of the scheduled 205, for CO1 and tightness class BH, a situation occurred in which the shaft was unable to make a full rotation. The testing was stopped. To diagnose the problem, the shaft and sealing elements were disassembled in consultation with the customer. A preliminary inspection of the shaft already showed that it had seized. Further visual inspection and analysis of the gland chamber components led to the hypothesis that the cause was mechanical degradation of the bronze sliding washer. As a result of this damage, small pieces of the washer separated and got between the shaft and the seal.  The valve stem seized and stopped rotating, then the leakage rose to exceed the CH class (which means it rose more than 1000 times).
The expert report sent to the customer showed the need to change the material of the sliding washer, make a new shaft and apply a new seal, possibly redesigning the components related to the sealing system in the gland.

Measurement and testing services 'under real conditions'

An extension of the laboratory's offer is its services of testing equipment and systems in the field - at plants and facilities. Such services are intended for cases where testing services involve large equipment or where pressure vessels are permanently fixed to the system (e.g. welded) and/or with no possibility of disassembly - for example, due to the need to ensure the continuous operation of the plant. 

In the above situations, laboratory personnel perform leak testing of the system or parts of it 'in real conditions' at the customer's premises - at the installation site of the unit or system. Mobile test instruments allow the detection of leak locations and tightness measurements that determine emission values. 

Carrying out tasks in real operating conditions means that our services are not limited by the dimensions of the equipment which are being tested or the size of our laboratory facility. On the other hand, the fact that the system does not have to be shut down means significant savings in terms of time and cost - during testing, the plant can operate normally with full availability and functionality of the component undergoing testing. 
 

Photo 5 Running the periodic testing of safety valves in the field during normal operation is done without stopping the work of the machinery or system

 

A special type of service conducted by our laboratory 'under real conditions' is safety valve performance testing. Given the popularity of this type of valve and the need for regular inspection, it is the periodic testing of safety valves conducted 'during normal operation' that is the most popular mobile testing service provided by SPETECH® Laboratory.