Technical Info / Inside Tests  
 
    IN HOUSE TESTS
  HELIUM LEAK DETECTION TEST
  MAKE / REMAKE TEST INTERCHANGEABILITY
  HYDRAULIC PRESSURE AND BURST TEST
  THERMAL SHOCK TEST
  VIBRATION TEST
 
   
  IN HOUSE TESTS  
 
  • Tests were conducted in HAM-LET laboratories. Each test was designed and programmed carefully.
  • All tests were designed so as to eliminate any leakage of safety hazards in fluids and gases systems.
    Planning of tests and using calibrated measuring tools, assures
    our reliable test results.
 
  Test program:  
  • Helium leak test.
  • Make / remake tests including interchangeability.
  • Hydraulic pressure and burst test.
  • Thermal shock test.
  • Vibration test.
  • These tests are conducted on a regular basis during production.
 
  HELIUM LEAK DETECTION TEST  
 

Helium leak detection test was conducted as per HAM-LET procedure 3103 with the ASM 180 TD leak detector "Alcatel" France (sensitivity to 5x10-12 bar cc/sec).

  
     
 

The fitting was assembled on the suitable tube according to the installation procedure.

Helium leak detector was calibrated. High vacuum inside the system was conducted before inserting helium around the fitting in a special bag.
Fittings and tubes of several dimensions were tested.

Test was repeated after 5 times for make/remake of the same assembly.
Test results (Table no. 2)
 
Test results:
Fitting Size
inch (mm)		 Helium leak
(bar cc/sec)		 Time
(min.)
1/4 (6) 1 x 10-9 5
3/8 (10) 1 x 10-9 5
1/2 (12) 2 x 10-9 5
3/4 (19) 2.5 x 10-9 5
1” (25) 2 x 10-9 5
    
 
  MAKE / REMAKE TEST INTERCHANGEABILITY  
  Nuts and ferrules were assembled with a clean faced short tube,
inserted to the fitting body.
Assembly according to the installation procedure.
The next operations performed were:
Finger tight of the nut on the fitting body.
Clamping the fitting body on a vice and tightening 1.1/4 turns.
Releasing the nut and tube.
Inserting the tube back in a different orientation, tightening over 1.1/4 turns.		  
     
  Make / remake this tightening for 10 times and checking:  
 
   

5.1 Thread position and silver coating on the nut.
5.2 Sticking/non-sticking of parts.
5.3 Conducting pressure test at 500 bar.
5.4 Conducting helium leak test with ASM 180TD leak detector.
 
     
  Changing nuts and ferrules made of HAM-LET and competitor in different positions.
Writing down the test results as following:
No leakage was found in pressure test.
No Helium leak was found over 2.10-9 bar cc/sec.
No sticking of parts; tube was pulled out easily.		  
     
 
Test
No.		 Size Nut Ferrules Body 10 mm
Remake		 No
calling		 11/4
tern
1 3/8" Competitor LET-LOK Competitor LET-LOK LET-LOK      
2 1/2"   +   + + OK OK OK
3 1/2"   +   + + OK OK OK
4 3/8"   +   + + OK OK OK
5 1/4"   +   + + OK OK OK
6 1/2"   +   + + OK OK OK
7 1/2"   +   + + OK OK OK
8 1/2"   +   + + OK OK OK
9 1/2" +   +   + OK OK OK
10 1/2" +       + OK OK OK
11 1/2" +   + + + OK OK OK
12 1/4"   +     + OK OK OK
13 1/4" +   + + + OK OK OK
14 1/4"   +     + OK OK OK
15 1/4" +   + + + OK OK OK
16 1/4" +       + OK OK OK
17 1/4"     + + + OK OK OK
 
   
  HYDRAULIC PRESSURE AND BURST TEST  
 

Pressure test was conducted to LET-LOK® fittings assembled according to the installation procedure.

Tested samples must stand a minimum hydraulic pressure of 1.5 times the maximum permissible working pressure. This pressure was held for 5 minutes.
In the same test the fixture (filled with water) pressure was raised up to tube burst.

No leakage or cracks were found in fittings.
Results are shown in table.

  
     
 
Nom. Size
mm (inch)		 Tube WT
mm (inch)		 Allowable
working
pressure
bar (psi)		 Test pressure
bar (psi)		 Time
(min.)		 Burst
Pressure
of Tube
bar (psi)
2 (1/16)
6 (1/4)
10 (3/8)
12 (1/2)
19 (3/4)
25 (1”)		 0.5 (0.02)
1.25 (0.049)
1.65 (0.065)
2 (0.078)
2.5 (0.095)
2.5 (0.098)		 475 (6881)
596 (8644)
520 (7538)
462 (6696)
364 (5288)
265 (3844)		 713 (10,340)
910 (13,195)
850 (12,325)
693 (10,050)
580 (8,410)
567 (8221)		 5
5
5
5
5
5		 1.900 (27,950)
2,200 (31,900)
1,850 (26,825)
1,848 (26,796)
1,150 (16,675)
1,250 (18,125)
 
     
  * Tube burst in all cases.
* No fitting was damaged.		  
 
 
   
  THERMAL SHOCK TEST  
  The test was conducted in 2 sub-tests:  
 
  • Leakage test with high pressure (500 bars).
  • Helium leak test.
  
  The fittings and tubes were assembled as per the installation procedure.
Cycles of high temperature to low temperature were performed.
Temperature difference was between -70°C to 100°C.
Changes of temperature were done in a very short time (within a few minutes), using cooling system and electric oven.		  
     
  Tests results were:
No leakage was found in the immersed pressurized fitting assembly in both temperatures.
Helium leak test in both temperatures was conducted on the ASM 180TD detector.
2 . 10-8 bar cc/sec (hot) and 4 . 10-9 bar cc/sec (cool) were the helium leakage in both temperatures.		  
   
  VIBRATION TEST  
 

Fitting was assembled according to the installation procedure, using a vibration test bench consisting of a non-concentric weight on a motor wheel, bearing clamped, connected to the tube. Getting through frequencies from 1-25 hz and checking the fitting after such stresses to both tests - helium leak test and pressure tests.

Results were as listed below:

  
 
Fitting size
Tube size WT
mm (inch)
Helium leak test
bar cc/sec
Pressure test
(500 bar)
1/4
3/8
1/2
3/4
1.25 (0.049)
1.65 (0.065)
2 (0.078)
2.5 (0.095)
2 x 10-9
2.5 x 10-9
1 x 10-9
2 x 10-9
No leakage detected
No leakage detected
No leakage detected
No leakage detected
 
     
   
     
 
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