| TO: |
All maintenance personnel. |
| FROM: |
The Fluid Power Safety Institute™. |
| SUBJECT: |
All hydraulic flanges are not created equal! |
Introduction -
The FPSI™ felt it necessary to draft this Safety Bulletin because we are aware of several people who apparently, because they were untrained, made terrible errors with regard to hydraulic flanges.
The errors could have caused failures that could have resulted in severe injury or death.
Actual Case History -
A diesel mechanic with no formal training in hydraulics, was assigned the task of replacing a hydraulic motor on a machine.
When he attempted to reconnect the hydraulic hoses to the new motor, he found that the bolt holes on the 4-bolt, split flanges did not align properly with the holes in the motor housing.
He reportedly assumed that the bolt holes in the new motor were drilled in the incorrect positions, so he decided to modify the flanges to realign the holes.
With nothing more than on-the-job training, he failed to realize that he was modifying an SAE Code 62 (6000 PSI/414 bar) 4-bolt flange to fit an SAE Code 61 (3000PSI/207 bar) motor flange pad because the new motor was incorrect for the application.
He unknowingly eliminated the one critical element that protected him from making the vital error of installing a 3000 PSI (207 bar) component in a 6000 PSI (414 bar) system – the bolt hole configuration!
The error was apparently detected before the machine was put into operation. |
Tell me More! -
Four factors must be considered when dealing with 4-bolt flange fittings:
| 1. |
The Society of Automotive Engineers (SAE), composed dimensional standards for 4-bolt hydraulic flanges. |
| 2. |
Caterpillar® departed from the SAE dimensional standard, and came up with a dimensional standard of their own.
The Caterpillar® dimensional standard is so similar to the SAE Code 62 dimensional standard, that maintenance personnel unfamiliar with Caterpillar® equipment routinely have difficulty determining one from the other. |
| 3. |
The French GAZ 4-bolt flanges are completely different to SAE flanges, and are most commonly found on Poclain® components. |
| 4. |
Last, and certainly not least, training for maintenance personnel is discretionary in the fluid power industry. Untrained people are invariably unaware of, amongst other things, SAE standards. |
The net result! Confusion that leads to situations that could cause severe injury, death, or substantial property damage.
The three most common types of hydraulic flanges are referred to as SAE Code 61, SAE Code 62, and Caterpillar® Code 62.
They are all 4-bolt flanges, and they are available in two standard configurations: split flange, and captive flange.
Split Flange versus Captive Flange -
There are two types of 4-bolt flanges - namely, split flange and captive flange.
A split flange is comprised of two separate flange halves, and a captive flange is a one-piece flange. The bolt-hole dimensions for these flanges are size-for-size identical.
It is absolutely critical for people associated with fluid power, especially those who work on fluid power systems, to be intimately familiar with the minute, but very distinctive and necessary differences between the three most common variations.
A lack of understanding of the minute dimensional and physical differences between these connectors can spell the difference between life and death!
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|
Comparative Dimensions of 4-bolt flanges -
Nominal
Flange
Size
|
CODE 61
|
CODE 62
|
Caterpillar®
|
Flange
O.D.
|
A
|
B
|
C
|
Flange
O.D.
|
A
|
B
|
C
|
Flange
O.D.
|
A
|
B
|
C
|
|
1/2
|
1.188
|
0.688
|
1.500
|
0.265
|
1.250
|
0.718
|
1.594
|
0.305
|
|
|
|
|
|
5/8
|
1.338
|
|
|
0.265
|
|
|
|
|
|
|
|
|
|
3/4
|
1.500
|
0.876
|
1.875
|
0.265
|
1.625
|
0.938
|
2.000
|
0.345
|
1.625
|
0.938
|
2.000
|
0.560
|
|
1
|
1.750
|
1.030
|
2.062
|
0.315
|
1.875
|
1.094
|
2.250
|
0.375
|
1.875
|
1.094
|
2.250
|
0.560
|
|
1-1/4
|
2.000
|
1.188
|
2.312
|
0.315
|
2.125
|
1.250
|
2.625
|
0.405
|
2.125
|
1.250
|
2.625
|
0.560
|
|
1-1/2
|
2.375
|
1.406
|
2.750
|
0.315
|
2.500
|
1.438
|
3.125
|
0.495
|
2.500
|
1.438
|
3.125
|
0.560
|
|
2
|
2.812
|
1.688
|
3.062
|
0.375
|
3.125
|
1.750
|
3.812
|
0.495
|
3.125
|
1.750
|
3.812
|
0.560
|
|
2-3/4
|
3.312
|
2.000
|
3.500
|
0.375
|
|
|
|
|
|
|
|
|
|
3
|
4.000
|
2.438
|
4.188
|
0.375
|
|
|
|
|
|
|
|
|
|
3-1/2
|
4.500
|
2.750
|
4.750
|
0.442
|
|
|
|
|
|
4
|
5.000
|
3.062
|
5.125
|
0.442
|
|
|
|
|
|
5
|
6.000
|
3.624
|
6.000
|
0.442
|
|
|
|
|
|
|
|
|
In addition to the bolt-hole, center-to-center dimensions, there are additional physical differences between the SAE Code 61, SAE Code 62, and Caterpillar® 4-bolt flanges.
To illustrate how dimensionally similar the SAE Code 61 (3000 PSI/207 bar), and SAE Code 62 (6000 PSI/414 bar) 4-bolt flanges are, we have superimposed an SAE Code 61 flange over an SAE Code 62, using a 1" flange as an example.
The "A" dimension of the SAE Code 61 differs from the same dimension of a SAE Code 62 by a meager 0.064", and the "B" dimension by a scant 0.188". |
|
Beware of the "step-height" dimension on Caterpillar® 4-bolt flanges! -
In addition to the dimensional differences between the SAE Code 61, and the SAE Code 62, maintenance personnel who work around Caterpillar® equipment must be familiar with yet another dimensional variation.
Caterpillar® flanges share the identical outside diameters as the SAE Code 62 flanges. However, all Caterpillar® flanges share the same step height (dimension "C"), while the step height of the SAE Code 62 flanges differs for each size.
Beware of the French GAZ standard! -
The French GAZ 24º high-pressure flange is usually found on Poclain® equipment. They are completely different to SAE flanges. |
|
What immediate action must I take to avoid this type of accident? -
| 1. |
Attend a course of instruction in fluid power so you can become familiar with these, and other SAE standards. |
| 2. |
Exercise extreme caution when working with connectors, regardless of type. |
| 3. |
There are a number of extremely useful kits that are made for the exclusive purpose of correct connector identification.
The International Thread Identification Guide covers, in addition to 4-bolt, split flange connectors, most other types of hydraulic connectors from around the world. These are available from the following manufacturers:
• Gates® - part number 35095-H (5/91) - (contact your local dealer).
• Parker® offers a similar kit - (contact your local dealer).
|
| 4. |
Hydra-Check® offers a strong, durable Flange Identification Template for measuring and identifying SAE Code 61, SAE Code 62, and Caterpillar® flanges - (http://www.hydracheck.com) |
| 5. |
Discuss this problem in your safety meetings. |
| 6. |
If you are not sure - ASK! |
Conclusion -
Training is the first, and most vital step one can take in avoiding the problems addressed by the FPSI™ in these Maintenance Safety Bulletins.
Please pass this information along to others who may not have access to these bulletins. |
BACK
Waiver of Liability -
|
The Fluid Power Safety Institute™ does everything possible to ensure that the information and drawings contained in this safety notice are accurate, and the suggested procedures are deemed safe and reliable.
However, these are general recommendations only and might not be applicable to all situations.
You MUST have your engineering department in conjunction with your safety department read these recommendations and make the necessary changes for your application.
The Fluid Power Safety Institute™ is not responsible for actions taken by untrained and/or unauthorized persons.
Trained, authorized persons only should do ALL fluid power system service, repair, and troubleshooting.
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