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How do you get a box end wrench around a compression fitting? Unless you want to leave the wrench in place for the next guy, you’ll want a tool like one of Astro Pneumatic’s split box ratcheting wrenches.

Astro Pneumatics claims their wrenches allow you the access of an open-ended wrench while giving you the convenience of a ratcheting box-end wrench. They construct the heads of the wrenches from chrome moly steel, a steel alloy with chrome and molybdenum, for strength.

If you feel like getting sea-sick, by all means check out their instructional video. Don’t get me wrong — I love when companies shoot videos about how to use their products, but it seems to me that it might be worth the money to hire somebody who’s actually held a video camera before.

The wrenches come in a seven-piece Metric set, which includes 10mm, 12mm, 13mm, 14mm, 17mm, and 22mm wrenches — for some reason they only sell these wrenches in Metric. Pricing for the set starts in the neighborhood of $80.

Wrench Set [Astro Pneumatic]
Wrench Set [Northern Tool]
Street Pricing [Google Products]
Via Amazon [What’s This?]

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24 Responses to Split Box Ratcheting Wrenches

  1. Mark says:

    This is what flare nut wrenches were created for:

    These could have had the potential for better grip than a flare nut wnech but given that they are a 12 point design, I wouldn’t count on it.
    I would be concerned about rounding off the fitting.

  2. @Mark:

    I agree about flare nut wrenches, in fact I have the set, or at least a very similar set, that you linked to.

    I thought these were interesting for their claimed “ratcheting action, although I’m not exactly sure how these ratchet, as the video doesn’t really show them in action. I suspect in one direction the jaws are held shut by pushing in the wrench and in the other the jaws open and the nut slips in the jaws, potentially rounding them.

  3. FredP says:

    I don’t know about anyone else, but I have broken more than one flared nut wrench on lines that were incredibly tight. The basic design of the flared wrench means that that it’s not a strong structure.

    At least this wrench wraps around and holds the entire mechanism and nut in place during loosening.

  4. Not all flare nut wrenches are created equal. The cheap ones do break easy. The better ones (Snap-on, Craftsman, or what have you) seem to be made out of a much better grade of steel.

    Not that I have good ones… most of mine started out as cheap combo wrenches that I ground out when I found out I didn’t have a flare wrench that size.

  5. fred says:

    We carry sets of these on our plumbing trucks :

    COMPANY Part No UPC SIZE – Inches

    PROTO J3812 662679050764 3/8
    PROTO J3814 662679050771 7/16
    PROTO J3816 662679050788 1/2
    PROTO J3818 662679050795 9/16
    PROTO J3820 662679050801 5/8
    PROTO J3822 662679050818 11/16
    PROTO J3824 662679050825 3/4
    PROTO J3826 662679050832 13/16
    PROTO J3828 662679050849 7/8
    PROTO J3830 662679080856 15/16
    PROTO J3832 662679050863 1

    The list above is from my inventory – and we seem to have all Proto-brand ratcheting flare wrenches. We also carry several standard flare wrenches made by others (Fairmount-Martin Tools to name one supplier). We use these on plumbing fixtures (WC’s etc.) not autos – so I can’t comment on automotive applications. The ratcheting kind work well on the sizes they cover. Naturally – some old work fittings are so corroded that they need to be cut out entirely.

  6. rg says:

    These are probably a good concept, in that the harder you pull, the harder they squeeze. Not crazy about the 12-point construction, especially if you are working with brass or mild steel fittings.

    I’m probably sounding like a shill for Canadian Tire, but I bought a set of Mastercraft Expresswrenches a few years ago to use for work, and I’ve never looked back. I mainly use them on stainless tube fittings, and they’ve never failed. A bit awkward to use until you get used to them, but once you get the hang of it, they really speed up your work. The best part is they’ll grab the hex evenly on 3 opposite sides. Obviously, that means you need more room to turn them, but I’ve never stripped anything with these yet. They look a little delicate, but they’re amazingly tough tools.


    Sadly, I’ve just discovered they’re no longer available! Time to write an angry letter to CT.

  7. David Bryan says:

    I was using the Imperial, or Parker, or Swagelok version of these almost 30 years ago on all kinds of compression fittings, and I had to stick around to see how the connections held up in service on steam, air, and process instrumentation lines. They work just fine.

  8. browndog77 says:

    As someone who installs approx. 100 dishwashers/month, these look interesting. In recent years the manufacturers/designers have seemingly forgot that the hand you squeeze under that machine actually needs to have a tool in it, not to mention some room to move. Whirlpool recently changed to a plastic hose-bib connection for water, but the others do not seem to want to follow. (not sure I blame them!)
    3 or 4 sizes are all I need, so I am on the market. As far as really tight nuts, there are cheaper & sturdier tools in the bag to break them loose first. I have a set of stubby combos for that.

  9. browndog77 says:

    Scratch that post! I missed the fact that that only metric sizes are available. Back to the search!

  10. @browndog77

    SK used to make a similar tools, in both Metric and fractional, but they seem to be discontinued. If you look around you might still be able to find some.

  11. David Bryan says:

    I looked at Stride Tools and couldn’t find the Imperial wrenches anymore, but Ridgid sells them in sizes 5/16 to 1″. Ratchet tube wrenches.

  12. fred says:

    @Benjamin Johnson and David Bryan

    I believe that the Proto’s that I listed above are still available.

    I also believe that our first set were Imperial Eastman brand – probably bought in the ’70’s

  13. Jimbo says:

    For amateur plumbers only, too gimiky… Stick with a good quality flare wrench.

  14. David Bryan says:

    Jimbo, I’ve known fitters that thought that anything more than a couple of crescent wrenches was getting too fancy. They thought flare nut wrenches were for little girls. These work all right.

  15. IndyEngineer says:

    These wrenches look clumsy, difficult, and cheap. I’ll stick to flare nut wrenches. Most nuts that you would use these on are made of brass or copper, I could see major problems with this wrench stripping the nut.

  16. browndog77 says:

    Like I said, 100 D/Ws/mo., & I do indeed get paid for all my services, as I have for 40+ years. If that’s amateur, I’ll wear the label! LOL If you strip a brass nut with any properly sized wrench, it’s too tight!

  17. Shopmonger says:

    Look like someone went….well they did it with a basin wrench…. ah hell plumbers will buy it. Could be good, but after working on hydraulics and 40year old cars…. flare wrenches are great and yes the cheap ones break…and i am am an imperial cheap ass and i still buy only craftsman or mac or snapon flares….. just so i don’t get my blood pressure in a boil too often. I also agree that on brass or copper this new tool concerns me a bit with 12 point…but maybe it work more like a star point socket…..hopefully someone will try it out…


  18. fred says:

    W’ve been using this type (USA Made Proto’s ) of wrench, in a commercial setting employing professional plumbers – for over 30 years. They improve productivity – and work in confined places where regular flare wrenches are cumbersome. Most of the fittings we use them on are brass or chrome plated brass. I have never been afraid of trying new tools – that might enhance productivity or improve safety. If they come from the automotive trade – or were designed for instrumentation lines (e.g. Hoke or Swagelock fittings) but work well on plumbing – who cares. BTW – Proto used to make plumbing tools like yarning and caulking irons – and sold just about the best internal pipe wrecheches (for pulling out broken or short nipples) that anyone made.

  19. fred says:

    A bit more searching on the web ad I see that the sets sell for quite a little bit more than the Astro Metric ones:


  20. Jimbo says:

    I’ve worked in the industry for over 38 years and gimiky gadgets only clutter up your toolbox. Not worth the extra weight. Stick with what works and works well.

  21. Mike says:

    We used these 40 years ago in the military to tighten up the sway braces that held bombs in place on bomb racks. We’d lock the box end around the nut then tighten it down until snug. We called them “Mexican speeders” back then. Worked pretty darn good, too! These little guys would be very handy working on cars as well as on plumbing.

  22. Mark says:

    Over my career as a import car mechanic I have used these wrenches from various manufactures (Imperial, Mac and Snap-On). I used them on brake line flare nuts and automatic transmission fill/dipstick flare nuts. Now retired and playing on old domestic cars I have needed some SAE sizes that I didn’t have for a P/S hose flare nut on a Saginaw P/S pump. I have searched the Internet for several days looking for these specialty wrenches. That is why I am posting to a 10 year old thread. Fred listed a few part numbers that I was able use to find what I needed to fix my old Corvette on ebay. The Internet never forgets!

  23. Angie says:

    thanks for this very detailed post.

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