Galvanize Steel Fitting Used on Hydraulic

[I Piddle]

I see quite a lot of 3/4 inch steel fitting on tractor hydraulics. My tractor has a few. I am wondering if these fittings are recommended for high-pressure hydraulics. They appear to be more durable than the brass and stainless steel fittings. They are rated at ASTM 53. As far as I can tell that is only 1000psi. We have been using steel for over 50 years on our hydraulic lines with no problem. Primarily for elbows and nipples. Just wondering if I am pushing my luck.

 

[npalen]

Seems like I heard years ago that galvanizing can flake off inside the pipe or fitting and cause problems. That may be just an old wives tale. (old farmers tale?)

 

[4570Man]

As you already realized pipe fittings aren’t rated for hydraulic pressure. But they apparently work because a lot of people are doing it.

 

[rScotty]

As you already realized pipe fittings aren’t rated for hydraulic pressure. But they apparently work because a lot of people are doing it.

I've wondered about the same thing, and with good reason since we have some of those old pipe fitting on our equally old JD FEL from the 1950s. I think a lot of people got by back then with using plumbing fittings because of two reasons - the most important one being that hydraulics on old tractors didn't run at the pressures common today. Our old JD has a hydraulic pressure gauge so we know it does most of the loader work between 800 and 1000 psi. I don't think I've ever seen it go over 1250 psi, and not sure it can.

The other reason is although fittings back in the 1960s weren't rated for hydraulic use, US manufacturing was at a high point and quality was very good. It was a point of pride that "Made in USA" meant that it beat the specs in every way. Quality was a big selling point; more so than profits. Pipe fittings were no exception.

60 years ago I can't remember ever splitting a tapered pipe fitting when tightening it down - in spite of being young, strong, and stupid. In the last few years I've split several pipe and gas fittings just doing normal tightening.

I wouldn't use any modern pipe fittings on that old John Deere. If I replace one it will be with a hydraulic fitting. And I sure wouldn't use anything except fully rated genuine hydraulic fittings on our Kubota with its much higher psi.
rScotty

 

[LD1]

Id avoid galvanized.

Pipe fittings are ok for return and suction side. But stick to hydraulic rated fittings for the pressure side

 

[kennyd]

Newer cast pipe fittings from places like Home Cheapot are rated for like 300PSI, not even the 1000 you stated. No way should they be used in hydraulic service.

 

[mikester]

I wouldn't bet my life or limb on a cast iron fitting..especially one made in china or india from scrap tin cans and who knows what else

 

[Menagerie-Manor]

I see quite a lot of 3/4 inch steel fitting on tractor hydraulics. My tractor has a few. I am wondering if these fittings are recommended for high-pressure hydraulics. They appear to be more durable than the brass and stainless steel fittings. They are rated at ASTM 53. As far as I can tell that is only 1000psi. We have been using steel for over 50 years on our hydraulic lines with no problem. Primarily for elbows and nipples. Just wondering if I am pushing my luck.

As long as it's a forged steel 90 deg ell pressure ratings should not be an issue as they are typically rated for 3000# plus. No need for galvanizing on forged steel fittings.

 

[oldnslo]

Seems like I heard years ago that galvanizing can flake off inside the pipe or fitting and cause problems. That may be just an old wives tale. (old farmers tale?)

Not a wives tale Galvanizing will flake off when used on hydraulics.

 

[I Piddle]

I see quite a lot of 3/4 inch steel fitting on tractor hydraulics. My tractor has a few. I am wondering if these fittings are recommended for high-pressure hydraulics. They appear to be more durable than the brass and stainless steel fittings. They are rated at ASTM 53. As far as I can tell that is only 1000psi. We have been using steel for over 50 years on our hydraulic lines with no problem. Primarily for elbows and nipples. Just wondering if I am pushing my luck.

Thanks for all of the replies. I found this on the net. I assume they are referring to just steel pipe. But it is hard to determine the quality of pipe with so much stuff coming from China these days. Even the fittings sold as hydraulic fittings may not be certified for the rating they claim.

Hydraulics :​

Piping specs and Safety​

The pressure ratings I posted yesterday came from a reference commonly used in the hydraulic industry and were stated for ASTM A53 welded and seamless pipe. Looking in other references and texts today, I find different burst pressures for seamless pipe. Since the majority of the references call for the higher pressures for seamless, I will post those here. Each person must decide what factor of safety they want to use. What I do for myself may not be the same as what you will want to do. There are MANY factors that affect the pressure rating of pipe. I suggest, as I did yesterday, that an informed individual uses at least a 6 to 1 factor of safety on burst pressure for properly installed new pipe. Below are the numbers that have two good references in agreement. These would be 6 to 1 on the stated burst pressure for ASTM A53 grade B SEAMLESS and ASTM A106 grade B which is also seamless. Note that welded pipe will have lower pressure capability.

1/2" ASTM A53 grade B type S and ASTM A106 grade B schedule 40 2600 psi

3/4" ASTM A53 grade B type S and ASTM A106 grade B schedule 40 2150 psi

1/2" ASTM A53 grade B type S and ASTM A106 grade B schedule 80 3500 psi

3/4" ASTM A53 grade B type S and ASTM A106 grade B schedule 80 2933 psi

All good pipe is identified on the outside of the pipe. Usually with a paint or ink marking. ASTM is the most recognized pipe spec. Any pipe not identified on the outside or not readable should NOT be used for hydraulics. There are pipe size tubings out there that are real junk and will not hold pressure. Some are sold in home centers as pipe.

ASTM A53 covers both welded and seamless black and galvanized pipe. ASTM A106 is only seamless and usually for high temp service, but it can be used for hydraulic systems. The grade identifies the minimum strength of the pipe material. You want at least grade B. Grade A is lower strength.

There are also API specs. API 5/L Grade B is very similar to A53 Grade B type S. API 5/LX is stronger and better.