Accurate measurements are essential for hydraulic fittings, and using the right tools and techniques ensures precision.
1,How to Measure Stainless Steel Hydraulic Fittings
Measuring the Outside Diameter of Stainless Steel Hydraulic Fittings
First, clean the hydraulic fittings thoroughly to ensure accurate measurements. Use tools like calipers or deep socket gauges to measure the outside diameter. Make sure to measure at two opposite points to avoid errors.
Be careful to select the correct measuring position. Measuring at a bend or bulge will give a larger size, while depressions will show a smaller size.
Measuring the Diameter of Stainless Steel Hydraulic Tube
To measure the diameter of hydraulic tube fittings, use the same gauge as for the fittings. Insert the gauge through the center of the hydraulic tube to get an accurate measurement.
Again, it’s crucial to choose the right measuring spot to avoid inaccuracies due to bumps or depressions in the tube.
Measuring the Stainless Steel Hydraulic Fitting Thread Size
For thread size, use an appropriate caliper or thread gauge. Place the tool over the threads and measure the thread diameter based on the number of thread turns. To measure the thread pitch, position the gauge between the peaks of the hydraulic fitting threads.
2,Common Measuring Instruments
- Calipers: Traditional tools that measure outside and inside diameters, though they offer less accuracy.
- Tape Measure: Another traditional tool that can measure length, outside diameter, and inside diameter.
- Double Parallel Line Caliper: A special tool for measuring the outside diameter of threads with high accuracy.
- Digital Display Caliper: Provides higher accuracy than traditional calipers thanks to its digital display.
- Digital Display Advanced Double Parallel Line Calipers: Used for measuring the outside diameter of threads with even greater accuracy.
3,Hydraulic Fitting Thread Sizes and Tolerance Tables
Metric thread basic dimensions and tolerances (tooth angle 60°) M
| Metric thread basic dimensions and tolerances (tooth angle 60°) M | ||||||||||||||||
| Thread | base diameter | internal thread | external thread | |||||||||||||
| large diameter | Middle diameter | Small diameter | tolerance level | tolerance level | ||||||||||||
| 6H | 7H | 6g | ||||||||||||||
| Middle diameter | Small diameter | Middle diameter | Small diameter | Middle diameter | large diameter | |||||||||||
| tolerance | tolerance | tolerance | tolerance | tolerance | tolerance | |||||||||||
| M10x1 | 10 | 9.35 | 8.917 | 0,+0.150 | 0,+0.236 | 0,+0.190 | 0,+0.300 | -0.026,-0.138 | -0.026,-0.206 | |||||||
| M12x1 | 12 | 11.35 | 10.917 | 0,+0.160 | 0,+0.236 | 0,+0.200 | 0,+0.300 | -0.026,-0.144 | -0.026,-0.206 | |||||||
| M14x1 | 14 | 13.35 | 12.917 | 0,+0.160 | 0,+0.236 | 0,+0.200 | 0,+0.300 | -0.026,-0.144 | -0.026,-0.206 | |||||||
| M12x1.25 | 12 | 11.188 | 10.647 | 0,+0.180 | 0,+0.265 | 0,+0.224 | 0,+0.335 | -0.028,-0.160 | -0.028,-0.240 | |||||||
| M14x1.25 | 14 | 13.188 | 12.647 | 0,+0.180 | 0,+0.265 | 0,+0.224 | 0,+0.335 | -0.028,-0.160 | -0.028,-0.240 | |||||||
| M12x1.5 | 12 | 11.026 | 10.376 | 0,+0.190 | 0,+0.300 | 0,+0.236 | 0,+0.375 | -0.032,-0.172 | -0.032,-0.268 | |||||||
| M14x1.5 | 14 | 13.026 | 12.376 | 0,+0.190 | 0,+0.300 | 0,+0.236 | 0,+0.375 | -0.032,-0.172 | -0.032,-0.268 | |||||||
| M16x1.5 | 16 | 15.026 | 14.376 | 0,+0.190 | 0,+0.300 | 0,+0.236 | 0,+0.375 | -0.032,-0.172 | -0.032,-0.268 | |||||||
| M18x1.5 | 18 | 17.026 | 16.373 | 0,+0.190 | 0,+0.300 | 0,+0.236 | 0,+0.375 | -0.032,-0.172 | -0.032,-0.268 | |||||||
| M20x1.5 | 20 | 19.026 | 18.376 | 0,+0.190 | 0,+0.300 | 0,+0.236 | 0,+0.375 | -0.032,-0.172 | -0.032,-0.268 | |||||||
| M22x1.5 | 22 | 21.026 | 20.376 | 0,+0.190 | 0,+0.300 | 0,+0.236 | 0,+0.375 | -0.032,-0.172 | -0.032,-0.268 | |||||||
| M24x1.5 | 24 | 23.026 | 22.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M26x1.5 | 26 | 25.026 | 24.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M27x1.5 | 27 | 26.026 | 25.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M30x1.5 | 30 | 29.026 | 28.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M33x1.5 | 33 | 32.026 | 31.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M36x1.5 | 36 | 35.026 | 34.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M39x1.5 | 39 | 38.026 | 37.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M42x1.5 | 42 | 41.026 | 40.376 | 0,+0.200 | 0,+0.300 | 0,+0.250 | 0,+0.375 | -0.032,-0.182 | -0.032,-0.268 | |||||||
| M27x2 | 27 | 25.701 | 24.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M30x2 | 30 | 28.701 | 27.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M33x2 | 33 | 31.701 | 30.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M36x2 | 36 | 34.701 | 33.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M39x2 | 39 | 37.701 | 36.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M42x2 | 42 | 40.701 | 39.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M45x2 | 45 | 43.701 | 42.835 | 0,+0.224 | 0,+0.375 | 0,+0.280 | 0,+0.475 | -0.038,-0.208 | -0.038,-0.318 | |||||||
| M52x2 | 52 | 50.701 | 49.835 | 0,+0.236 | 0,+0.375 | 0,+0.300 | 0,+0.475 | -0.038,-0.218 | -0.038,-0.318 | |||||||
| M60x2 | 60 | 58.701 | 57.835 | 0,+0.236 | 0,+0.375 | 0,+0.300 | 0,+0.475 | -0.038,-0.218 | -0.038,-0.318 | |||||||
| M64x2 | 64 | 62.701 | 61.835 | 0,+0.236 | 0,+0.375 | 0,+0.300 | 0,+0.475 | -0.038,-0.218 | -0.038,-0.318 | |||||||
| M72x2 | 72 | 70.701 | 69.835 | 0,+0.236 | 0,+0.375 | 0,+0.300 | 0,+0.475 | -0.038,-0.218 | -0.038,-0.318 | |||||||
Basic dimensions and tolerances for 55° English pipe threads (tooth angle 55°) G,PF,K,BSPP
| Basic dimensions and tolerances for 55° English pipe threads (tooth angle 55°) G,PF,K,BSPP | ||||||||||
| Basic Diameter | Internal Thread | External Thread | ||||||||
| tolerance level | tolerance level | |||||||||
| Grade | Thread | Middle diameter | Small diameter | A | B | |||||
| large diameter | Middle diameter | Small diameter | tolerance | tolerance | Middle diameter tolerance | large diameter tolerance | Middle diameter tolerance | large diameter tolerance | ||
| -2 | G1/8”x28 | 9.728 | 9.147 | 8.566 | +0.170，0 | +0.282，0 | 0，-0.107 | 0，-0.214 | 0，-0.214 | 0，-0.214 |
| -4 | G1/4”x19 | 13.157 | 12.301 | 11.445 | +0.125，0 | +0.445，0 | 0，-0.125 | 0，-0.250 | 0，-0.250 | 0，-0.250 |
| -6 | G3/8”x19 | 16.662 | 15.806 | 14.95 | +0.125，0 | +0.445，0 | 0，-0.125 | 0，-0.250 | 0，-0.250 | 0，-0.250 |
| -8 | G1/2”x14 | 20.955 | 19.793 | 18.631 | +0.142，0 | +0.541，0 | 0，-0.142 | 0，-0.284 | 0，-0.284 | 0，-0.284 |
| -10 | G5/8”x14 | 22.911 | 21.749 | 20.587 | +0.142，0 | +0.541，0 | 0，-0.142 | 0，-0.284 | 0，-0.284 | 0，-0.284 |
| -12 | G3/4”x14 | 26.441 | 25.279 | 24.117 | +0.142，0 | +0.541，0 | 0，-0.142 | 0，-0.284 | 0，-0.284 | 0，-0.284 |
| -16 | G1”x11 | 33.249 | 31.77 | 30.291 | +0.180，0 | +0.640，0 | 0，-0.180 | 0，-0.360 | 0，-0.360 | 0，-0.360 |
| -20 | G1.1/4”x11 | 41.91 | 40.431 | 38.952 | +0.180，0 | +0.640，0 | 0，-0.180 | 0，-0.360 | 0，-0.360 | 0，-0.360 |
| -24 | G1.1/2”x11 | 47.803 | 46.324 | 44.845 | +0.180，0 | +0.640，0 | 0，-0.180 | 0，-0.360 | 0，-0.360 | 0，-0.360 |
| -32 | G2”x11 | 59.614 | 58.135 | 56.656 | +0.180，0 | +0.640，0 | 0，-0.180 | 0，-0.360 | 0，-0.360 | 0，-0.360 |
| -40 | G2.1/2”X11 | 75.184 | 73.705 | 72.226 | +0.217，0 | +0.640，0 | 0，-0.217 | 0，-0.434 | 0，-0.434 | 0，-0.434 |
| -48 | G3”X11 | 87.884 | 86.405 | 84.926 | +0.217，0 | +0.640，0 | 0，-0.217 | 0，-0.434 | 0，-0.434 | 0，-0.434 |
Basic dimensions and tolerances for taper pipe threads (tooth angle 60°) NPT,Z
| Basic dimensions and tolerances for taper pipe threads (tooth angle 60°) NPT,Z | ||||||||||||||
| Thread code | Diameter on the base surface | Thread length | Diameter of the end face | |||||||||||
| Grade | large diameter | Middle diameter | Small diameter | Tube end to base length | Effective length | |||||||||
| -2 | Z1/8″x27 | 10.242 | 9.489 | 8.736 | 4.102 | 6.703 | 9.986 | |||||||
| -4 | Z1/4″x18 | 13.616 | 12.487 | 11.385 | 5.786 | 10.206 | 13.254 | |||||||
| -6 | Z3/8″x18 | 17.055 | 15.926 | 14.797 | 6.096 | 10.358 | 16.674 | |||||||
| -8 | Z1/2″x14 | 21.223 | 19.772 | 18.321 | 8.128 | 13.556 | 20.715 | |||||||
| -12 | Z3/4″x14 | 26.568 | 25.117 | 23.666 | 8.611 | 13.861 | 26.03 | |||||||
| -16 | Z1″x11.5 | 33.228 | 31.461 | 29.694 | 10.16 | 17.343 | 32.593 | |||||||
| -20 | Z1.1/4″x11.5 | 41.985 | 40.218 | 38.451 | 10.668 | 17.953 | 41.318 | |||||||
| -24 | Z1.1/2″x11.5 | 48.054 | 46.287 | 44.52 | 10.668 | 18.377 | 47.387 | |||||||
| -32 | Z2″x11.5 | 60.092 | 58.325 | 56.558 | 11.074 | 19.215 | 59.4 | |||||||
| -40 | Z2.1/2”x8 | 72.699 | 70.159 | 67.619 | 17.323 | 28.892 | 71.616 | |||||||
| -48 | Z3”x8 | 88.608 | 86.068 | 83.528 | 19.456 | 30.48 | 87.392 | |||||||
