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We are daily using the equipment which was developed and produced in L-plan like Conformity Assessment – Inspection Body, pressure equipment area.

The Legaline testing / measuring methods and devices are designed according to:

• EN ISO/IEC 17025,
• EN ISO/IEC 17020).

And:

Because of motor consumption monitoring and factory calibration with force, some advantages have been made:

• System overload protection – the maximum motor pulling force is mechanically limited so that the respective deign values of the components are not exceeded
• Power monitoring – an electronic system monitors if the supplied current and tension meet the requirements of the test conditions
• Power calibrating function – protect the system in the case of force sensor failure indication with factory calibration (comparison) of motor electric consumption with force chain values.

Some independent monitoring is done by Legatest hardware:

This monitoring also include emergency shutdown. In the case of dangerous and unexpected situation occurs, Legatest drive automatically close the valve.

• Examples: unexpected cable suspension, communication lost, low battery and other.
• Excessive temperature protection – temperature is monitored. If the temperature value exceeds the operating limits the system it is automatically shut off.

Because of Legatest PC software and sensors some other safety protections are applied:

• Sensors overload protection – the maximum motor force is limited by the force sensor measuring range
• Valve overload protection – the maximum force applied to the valve is calculated from the valve data.
• Maximum lift limitation – the maximum lift of the valve disk can be limited through the valve parameters.
• Based on entered valve data, software helps to select right sensors…
• And other…

Testing phase can be automated.

After the valve set point is reached, several limitations turned down the spindle in start position. Special sensor measure the Legatest spindle position.

Calculations, results and diagrams are processed immediately:

• Opening pressure
• Closing pressure (only HOT test)
• Blow-down
• Opening difference (between declared and measured) % and bar
• Minimum / maximum pressures
• Measurement uncertainty (if required) +-% and bar
• And other if are required…

Read more advantages regarding of on-line safety relief valves testing with Legatest!

Božo Legat

For on-line pressure safety valves testing, motor drive have several advantages verso hydraulic drives. Here are some explanations on your questions raised:

The safety valve is not closed after the test. We don’t have enough difference between system working pressure and safety valve opening point! How to overcome this unpleasant situation?

Yes, this is large benefit of Legatest drive fast response. How?

Legatest technology and fast response allows fast determination of safety valve opening pressure while the expansion of steam power does not constitute such a force on the valve plug parts that would lead to full stroke. In this point the valve plug fast turn back to the valve seat.

In this case there is much less possibility of contamination of the valve and consequently leaks after the test.

Also the system pressure and medium losses are smaller.

However, acoustic sensor technology allowed the determination of leakage differences before and after the on-line test.

Opening pressure is sometimes hard to determine when the hidraulic drive is used. Why?

Motor drive has superior dynamic properties which reflect the following characteristic:

• Better control of pulling force.
• No negative hydraulic influences which may prevent proper and accurate determination of safety valve opening pressure and other functional characteristics.

How motor drive influences on safety of work?

Because of motor consumption monitoring and factory calibration with force, some advantages have been made:

• System overload protection – the maximum motor pulling force is mechanically limited so that the respective deign values of the components are not exceeded
• Power monitoring – an electronic system monitors if the supplied current and tension meet the requirements of the test conditions
• Power calibrating function – protect the system in the case of force sensor failure indication with factory calibration (comparison) of motor electric consumption with force chain values.

The valves are sometimes installed in very inaccessible areas. Management of the test should be done so by vast distances.

Legatest motor drive technology enables management and monitoring the test on a long distance (standard 50 m, 10mm or longer is possible). Communication connection between PC and Legatest drive with cables diameter 4 mm is quickly and easily unlike thick hydraulic hoses.

Communication speed is 30 ms in opposite of hydraulic slower response and hysteresis.

Slow communication reduces on-line testing safety!

The on-line testing with Legatest could be extremely effective due implemented technology and design parts.

28 safety valves on line testing in one day – Legatest client record from Germany.

Using the hydraulic device, these safety, accuracy and useful features cannot be implemented.

How is the power supply? In some environments it is difficult to access or prohibited because of potentially explosive areas…

Legatest device is power autonomous. Near motor drive accumulator batteries are mounted. With full charged batteries 200 normal on-line safety valves tests can be implemented (50 tests up to 50 kN).

Legatest device can be use in potentially explosive atmospheres according to directive 94/9/EC, approvals include:

• EC Type Examination Certificate Nr: SIQ 11 ATEX 134 X for Ex cones: II 2 G Ex d(ib) ib IIC T4 Gb
• Under manufacturing, each device separately is approved: Certificate of Conformity Nr: LT III Eex….

See more about In-Situ Safety Relief Valves Testing…

Božo Legat

With a special high accuracy testing device like Legatest, yes, of course!

Legatest electronic system is made from high quality components to maintain adequate measurement properties at variable temperatures of use.

By keeping the requirements of the standard EN ISO 4126-1:2013, chapter 7.2.3: »The uncertainty of pressure measurement shall be within +- 0,5 % in the temperature range between -15°C up to 60°C.«. How is it possible?

With an innovative approach to some limitation overcome:

By measurement uncertainty automatic determination

According to L-PLAN Legatest procedure P11;5.4.11 Analysis and procedure for measurement uncertainty calculation meet requirements from EURAMET, DKD, EA…,.

Legatest system and software includes function of measurement uncertainty automatic calculation, based on:

• Used measurers and measurers chain influences
• Environmental influences
• Testing influences
• Measuring influences: resolution, force increasing speed…
• Middle seat diameter error regarding on real sealing is taken into account.

Legatest electronic and environmental temperature are monitoring via temperature sensors also to avoid the testing out of the temperature range.

Temperature validation (document RA11; 5.4.10 Legatest validation report) was performed and accepted by Slovenian Accreditation institute (member of International Laboratory Accreditation Cooperation) according to international standard EN ISO/IEC 17020, which shall be implemented in L-PLAN Company like Conformity Assessment – Inspection body and manufacturer of device Legatest.

Also between different laboratories comparisons are periodically done.

By force measurement chain accuracy compensation:

Force sensors and Legatest force electronic calibration resultants can be promptly compensated by calibration correction factors.

With an innovative approach in the introduction of testing methods during operation.

• The Legatest device protection functions
• The safety valve and process pressure systems protection functions
• Several monitoring functions

With a daily using the Legatest device for on-line safety valve testing like Conformity Assessment – Inspection body since 1996!

On-site safety relief valves testing can be very accurate also because of it is performed in real process pressure equipment operating conditions which are safety valves exposed:

• Process system temperature
• Accumulation and flow capacity
• Compliance of the back pressure
• And other process pressure equipment performance influences.

And:

• The results are reproducible and cannot be manipulated.
• Reports generated all relevant input data, test results and the respective diagrams, testing time and date.
• The readjustment of opening pressure can be done easily.

This method is used more than 30 years.

With a very good knowledge of the operation of safety valves and process pressure equipment:

L-PLAN is Accredited Conformity Assessment Body – Inspection Body in the field of Pressure Equipment, as same as safety and other valves Testing / Inspection and pressure gauges Testing / Inspection.

Since 1991, Inspection, testing experiences are successfully included into the innovative development and production of measurement, test, calibration and inspection devices as same as methods and procedures.

1992 L-PLAN was the first in the world with the Safety Valve Data Acquisition Testing System.

We and also many clients are using the Legatest series devices every day. So the L-plan developed devices are constantly being improved.

We don’t produce the test units serial!

We try to adapt your requirements, ideas and specifics pressure equipment working roles.

Legatest on line testing device has several approvals. In addition to the device certification particularly is very important also on-line testing method approval.

See on line safety valves testing device Legatest approvals…

More about On-line pressure safety valves testing ….

Božo Legat

Safety valves are installed on process pressure equipment to release excess pressure due to faulty process operations, external fires and other hazards.

When all other safety and control devices collapse, the safety valve is last to release excess pressure and protect the scope of pressure equipment from explosion. So, safety valve serves to protect life and property.

Failure of pressure safety valves to function properly could result in the serious damage of vessels, exchangers, boilers, or other equipment. It is essential to maintain pressure safety valves and relief valves in good condition.

Periodic testing is one of the most important elements to ensure that the safety valves will provide this important protection.

On-line (on-site, in-situ, under operation pressure safety valves (safety relief valves…) is performed in real process pressure equipment operating conditions which are safety valves exposed:

• Process system temperature
• Accumulation and flow capacity
• Compliance of the back pressure
• And other process pressure equipment performance influences.

Therefore, the results of this method can be more accurate than the classical methods of testing the safety valves. A prerequisite is of course appropriate device and method that takes into account all the effects on the accuracy and credibility of the results in an unfavorable, industrial environment.

Method and device Legatest fulfills these conditions and it is at this moment on the world top position.

Why then on-line pressure safety valves testing?

Less shut downs – less production loss!

No system discharges – no fuel costs!

That so, improves the environmental conditions!

No raising the system pressure:

• No fuel consumption!
• No increasing the production noise level.
• Expand plant lifetime – No material / joints stress damages! Damage like valve seat erosion or deposits in boiler tubes is considerably reduced.

No dismantling the safety valves from the system – We save time and money:

• Welded S. valves – the cost for cutting and subsequent welding and weld inspections are avoided.
• Maintenance of valves on hardly accessible and distant locations becomes easier.
• New seals are not required!

 Testing / Inspection is possible at any time under any conditions, winter or summer.

Safety valves can be tested / inspected while the plant is operating (HOT TEST) or while it is shut down (COLD TEST).

Possibility of determination of valve condition before plant shut down.

Some standard valve indication also could be examined:

• Effect of the nozzle and guide ring.
• Spring and internal parts condition.
• Increasing of leakage after valve activation

By using the best testing equipment, the safety r. valves functions can be monitored and tested with greater accuracy, than conventional PSV testing on the test bench!

More about On-Line (On-Site, In-Situ, Under operation) safety valves testing…

Božo Legat