Details

The Hydraulic Snubber Test Bench is a cutting-edge testing solution engineered by Neometrix Defence Limited to ensure the performance and reliability of hydraulic and mechanical snubbers. These components play a critical role in safeguarding piping systems, nuclear power plants, and other sensitive infrastructure against seismic forces and dynamic loads.

This advanced facility is designed for in-service inspections (ISI) of snubbers, as mandated by ASME BPVC Section XI standards. It ensures that snubbers maintain their performance over their  perational life, providing reliable support to systems with diameters ranging from 15 NB to 800 NB. Load capacities vary between 17.5 KN and 240 KN, and stroke lengths range from 140 mm to 245 mm, depending on application requirements.


Key Features and Technical Specifications
The Hydraulic Snubber Test Bench incorporates advanced engineering and high-precision technologies to deliver exceptional performance and versatility:
▹ Snubber Compatibility: Hydraulic and Mechanical snubbers.
▹ Load Frame Stiffness: 1500 MN/m for robust and reliable load testing.
▹ Test Load Capacity: Designed to handle up to 25 tons, accommodating a wide range of snubber sizes and types.
▹ Velocity Range: Adjustable from 0.1 mm/sec to 15 mm/sec, replicating operational dynamics with precision.
▹ Acceleration Capacity: Up to 250 mm/sec², enabling realistic simulation of rapid dynamic loads.
▹ Beam Length Adjustment: Up to 1200 mm, suitable for various snubber sizes.
▹ Hydraulic Beam Locking Mechanism: Positive hydraulic clamp, which remains securely locked even without  hydraulic pressure.
▹ Stroke Length Range: Configurable between 50 mm and 300 mm to match different snubber designs.
▹ High-Precision Servo Actuator: Supports loads up to 50 tons, ensuring accurate and consistent force application.
▹ Hydraulic Power Pack Pressure: Capable of generating pressures up to 300 bar for efficient operation.
▹ Software and Control System: LabVIEW software paired with NI/PLC hardware for seamless operation and  data acquisition.

Advanced Test Capabilities
The Hydraulic Snubber Test Bench offers a comprehensive range of testing functionalities to evaluate snubber performance meticulously:
▹ Free Working Stroke Measurement: Ensures the snubber operates within its specified range without restrictions.
▹ Drag and Breakaway Force Assessment: Evaluates the force required to initiate movement, ensuring proper responsiveness.
▹ Blocking Speed and Activation Level Verification: Tests the snubber's response to rapid dynamic forces and activation thresholds.
▹ Drift Speed Analysis: Measures movement under sustained loads to verify stability and reliability.
▹ Spring Rate Determination: Assesses the stiffness and energy absorption characteristics of the snubber.
▹ Lost Motion Evaluation: Identifies any gaps or delays in response, ensuring precise operation under load conditions.

Applications
The Hydraulic Snubber Test Bench supports performance evaluation for snubbers used in high-stakes environments, ensuring optimal functionality and safety. Typical applications include:
▹ Nuclear Power Plants: Protecting reactors and piping systems from seismic forces and operational stresses.
▹ Sodium Piping Systems: Enhancing stability and reliability in dynamic environments.
▹ Critical Infrastructure: Providing robusport to power plants and other facilities during seismic events or under heavy operational loads.
The facility is ideal for routine quality assurance and in-service inspections to ensure long-term reliability and compliance with safety standards.

Snubber Details
Details of various snubbers are given in table-1


    
Table-1: Snubbers Details
    

        

            
S. No.
            
Snubber Designation
            
Snubber Type
            
Load SSE (kg)
            
Load OBE (kg)
            
Approx. Snubber Dimension (mm)
            
Stroke about mean position (mm)
            
Expected Sensitivity (mm)
            
Expected Lost motion (mm)
            
Expected Drag Force (kgf)
            
Expected Drift speed (mm/sec)
            
Test Load (Te)
        
    
    

        

            
1
            
K1-S1
            
Mechanical
            
200000
            
133000
            
1100
            
+50/+50
            
196mm/sec
            
<1
            
<260
            
0.4-2
            
20
        
        

            
2
            
K1-S2
            
Mechanical
            
20000
            
12000
            
750
            
+90
            
196mm/sec
            
<1
            
<240
            
0.4-2
            
12
        
        

            
3
            
K1-S3.1
            
Mechanical
            
10000
            
6000
            
800
            
+90
            
196mm/sec
            
<1
            
<120
            
0.4-2
            
6
        
        

            
4
            
K1-S4
            
Mechanical
            
5000
            
3000
            
520
            
+75
            
196mm/sec
            
<1
            
<60
            
0.4-2
            
3
        
        

            
5
            
K1-S5.1
            
Mechanical
            
2500
            
1500
            
550
            
+90
            
196mm/sec
            
<1
            
<30
            
0.4-2
            
1.5
        
        

            
6
            
K1-S5.2
            
Mechanical
            
2500
            
1500
            
595
            
+90
            
196mm/sec
            
<1
            
<30
            
0.4-2
            
1.5
        
        

            
7
            
K1-S3.2
            
Mechanical
            
10000
            
7250
            
738
            
+75
            
196mm/sec
            
<1
            
<145
            
0.4-2
            
7.25
        

        

            
8
            
K3-S1
            
Hydraulic
            
200000
            
60000
            
967.5
            
+75
            
2–6 mm/sec
            
<1
            
<1200
            
0.2–2
            
20
        
        

            
9
            
K3-S2
            
Hydraulic
            
20000
            
10000
            
785
            
+75
            
2–6 mm/sec
            
<1
            
<200
            
0.2–2
            
10
        
        

            
10
            
K3-S3.1
            
Hydraulic
            
10000
            
5000
            
665
            
+75
            
2–6 mm/sec
            
<1
            
<50
            
0.2–2
            
5
        
        

            
11
            
K3-S4
            
Hydraulic
            
5000
            
2500
            
620
            
+75
            
2–6 mm/sec
            
<1
            
<50
            
0.2–2
            
2.5
        
        

            
12
            
K3-S5.1
            
Hydraulic
            
3000
            
1500
            
630
            
+75
            
2–6 mm/sec
            
<1
            
<30
            
0.2–2
            
1.5
        
        

            
13
            
K3-S5.2
            
Hydraulic
            
3000
            
1500
            
630
            
+75
            
2–6 mm/sec
            
<1
            
<30
            
0.2–2
            
1.5
        
        

            
14
            
K3-S3.2
            
Mechanical
            
10000
            
5000
            
800
            
+75
            
196mm/sec
            
<1
            
<100
            
0.4–2
            
5
        




        

            
15
            
K5-S1
            
Hydraulic
            
225000
            
150000
            
1191
            
+75
            
2–6 mm/sec
            
<1
            
<300
            
0.2–2
            
20
        
        

            
16
            
K5-S2
            
Hydraulic
            
150000
            
100000
            
971
            
+75
            
2–6 mm/sec
            
<1
            
<200
            
0.2–2
            
10
        
        

            
17
            
K5-S3
            
Hydraulic
            
15000
            
10000
            
701
            
+75
            
2–6 mm/sec
            
<1
            
<200
            
0.2–2
            
10
        
        

            
18
            
K5-S4
            
Hydraulic
            
15000
            
10000
            
701
            
+75
            
2–6 mm/sec
            
<1
            
<200
            
0.2–2
            
10
        
        

            
19
            
K5-S5
            
Hydraulic
            
5100
            
3400
            
601
            
+75
            
2–6 mm/sec
            
<1
            
<50
            
0.2–2
            
3.4
        
        

            
20
            
K5-S6
            
Hydraulic
            
5000
            
3000
            
601
            
+75
            
2–6 mm/sec
            
<1
            
<50
            
0.2–2
            
5
        
        

            
21
            
K5-S7
            
Hydraulic
            
30000
            
20000
            
781
            
+75
            
196mm/sec
            
<1
            
<400
            
0.2–2
            
20
        
    



Snubbers Other Than Specified Above
The test facility has capability and provision for testing of snubbers other than specified under clause 6.1. These snubbers can be of any make and type (i.e. mechanical or hydraulic) within specified load capacity, maximum pin to pin distance, maximum snubber dimensions (Diameter/height etc.) and maximum stroke of test facility. Suitable arrangement (e.g. bolted flange connection) shall be provided in test facility for easy mounting of such snubbers.

There is provisions in the snubber test program (software) to suitably test such snubbers by specifying additional input parameters viz., type of snubber, snubber tag no., pin to pin distance, stroke, test load & expected values of sensitivity, lost motion, drag force, drift speed etc. Test facility shall have suitable provision for specifying such additional parameters for these snubbers in a user friendly/interactive manner. The software should be capable of conducting all required tests specified by user.

Snubber Tests And Their Acceptance Criteria
The test facility is capable of carrying out tests specified under clause 4.0 in one direction mode (tension and compression) as applicable to particular test. There shall be provision of carrying out all tests (cl. 4.0) in required sequence as per approved procedure. User shall also have option to perform only selective (one or multiple) tests for each snubber. Software should have provision to allow such testing.

During testing all relevant data is collected by software for generation of plots for interpretation of specified tests. Acceptable values for various tests are provided in table-1. These values should be suitably built in software program. However, there shall also be provision for specifying type of snubber (hydraulic and mechanical) and different acceptable values of various parameters by user before start of test. Further, the user should also have option to select relevant parameters to be reported for each test for the purpose of generating automatic test report.

Free Operability - Drag Force & Stroke Measurement:
The snubber is extended and contracted at a slow speed under tension/ compression over full stroke range. The total stroke of snubber is to be measured as distance between completely retracted and completely extended position of piston. Speed of snubber movement shall be low (<1 mm/s) during entire stroke. Test facility shall ensure that there is no damage to snubber during test. Suitable report shall be generated specifying various relevant parameters.

Drag Force Measurement:
During free operability test, system records the resistance force under tension and compression. The system shall be capable of recording load and displacement data. The load encountered corresponds to the frictional load (Drag Force) of the snubber. The force required is expected to be less than 2% of the snubber rated load (level-B load). Load cell supplied should be able to measure drag force with reasonable accuracy. In case, the drag force exceeds the specified value, same should be alarmed/annunciated. Test facility shall also be able to process test information to find out lost motion in tension and compression direction during above test.
Acceptability of the snubbers shall be evaluated and suitable report shall be generated specifying various relevant parameters.

Sensitivity Measurement:
The sensitivity is determined by the sudden increase in load. This test requires moving snubber piston with an increasing speed (for hydraulic snubber) or acceleration (for mechanical snubber) in tension and compression. The mechanical snubber is expected to lock at an acceleration value of 0.02g or below. The hydraulic snubbers is expected to lock at a velocity of 2-6 mm/sec. There may be some variation in these data. The test facility design should have sufficient margin to take care of such variations. The test facility should be capable of generating velocity upto 10mm/sec and acceleration upto 0.035g. There shall be suitable provision in the test facility to limit the snubber movement before reaching its specified stroke, when snubber is tested for maximum acceleration/ velocity limit.

The test facility able to measure velocity and acceleration with reasonable accuracy. The computer shall generate an alarm/ annunciation if locking value does not fall in the pre-set range. The acceptability of the snubber is to be evaluated and suitable report shall be generated specifying various relevant parameters.

Drift Speed Measurement:
In earthquake or dynamic event, the snubbers become stiff and act like rigid supports. Under this condition the snubber drifts and drift speed is expected to be in between 0.2 to
2 mm/sec for hydraulic snubbers and 0.4 to 2 mm/sec for mechanical snubbers. Verification is to be done by applying a static load (snubber rated load/ specified test load) above locking speed/ acceleration with snubber approximately at mid-stroke and maintaining applied load for a sufficient time and the test shall end before 5mm before the snubber reaching end of stroke position to avoid any damage to snubber.

The computer generates an alarm/ annunciation if locking value does not fall in the pre-set range. The acceptability of the snubbers is to be evaluated and suitable report shall be generated specifying various relevant parameters.

Additional Details
The test facility is capable of testing all snubbers as per Table-1 and any other snubber (Hydraulic/ mechanical) for all relevant parameters specified under clause 4.0 within limitations of load and stroke of the test facility.

Suitable provisions is provided in test facility viz., adjustable loading base frame with suitable attachments for testing the entire range of specified snubbers as well as other snubbers, safety features to avoid damage to snubbers and injuries to personnel, provision of locking by positive hydraulic clamp (without hydraulic pressure), provision for manual testing of free operability and drag force even in case of failure of hydraulic system/testing software. Also under no circumstances, the snubber should see load higher than the test load specified during testing.

Test facility  have following minimum requirements:
Equipment–Snubber Test Facility for functional testing of snubbers (for 20 ton maximum locking load).
Loading device – Hydraulic cylinder for 20 ton capacity test facility capable of carrying out specified tests.
Stroke – Max ±125 mm about mean position (tensile & compressive) with adequate reserve travel margin.
Test speed (for hydraulic snubbers) – upto 10mm/sec.
Test Acceleration (for mechanical snubbers) – upto 0.035g.
There should be provision to set the required acceleration and velocity for the test to be carried out depending on the snubbers.
Test Load–Test load for each snubber is as per Table#1. It should be possible to define test load for other snubbers within specified maximum limits of test facility.
Hydraulic System – Suitable to carry out required testing on various snubbers mentioned above and any other snubber (mechanical/hydraulic) within specified maximum limits of test facility.

Necessary controls, instrumentations and auxiliaries suitable for various snubbers (mechanical as well as hydraulic) for carrying out all the specified tests shall be provided.

Instrumentation (Sensors and Signal Processing)
Load cell of adequate scale and overload shall be provided. It shall have capability to measure drag force values with low least count (refer table-1 for drag force values) and good accuracy.
Suitable sensors and instrumentation shall be provided to measure all relevant parameters viz., displacement, time, velocity, acceleration, load etc with adequate least count and accuracy.
Necessary instrumentation for monitoring health of test facility and preventive maintenance shall also be supplied.

Controls
Type – fully automatic Computer based.
Back-up power: for minimum 30 minutes shall be available.

Software – Dedicated software (Language: in English) for automatic execution of test programs (specified in cl 4.0), collecting of measured data, generating plots and automatic interpretation of results and test reports.

Testing interface is interactive/ user friendly and software ask for the type of snubber (mechanical/ hydraulic) to be tested. Accordingly, all specified tests, internal processing for input velocity/ acceleration, load-etc. shall be finalized by software. Later on it shall be indicated along with acceptance values for information. There shall be also provision to input acceptance parameters for different tests and same shall be indicated in report after test is completed.

Further software is capable for performing necessary calculation of parameters (viz. displacement, velocity and acceleration), processing all relevant data and generate suitable report regarding functionality of snubber covering various snubber tests. Software shall be also capable of carrying out test facility calibration.

Printer: Inkjet type. Suitable high end good quality color printer.
Manual controls - All essential operations through Push Button on Console.
Electric Power Supply: 415 V AC  3 phase 50 Hz
Computer Based System Power Supply: 
Power supply is in scope of customer. 24 V DC for electronics and 240 V AC for Computer is preferred. Suitable sockets for 240 V AC and utility power supply may be provided. 

Computer Hardware Requirement:
Computer (LAPTOP is preferred) shall be rugged and of reputed brand in latest configuration, graphics and sufficient memory hard disk (minimum 1TB), RAM (minimum 8GB) or Higher Configuration etc. and such that it can process, record, analyze in real time, present and save test data.