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Metric NPT fittings

Discussion in 'General Industry Questions' started by Welder Dave, Oct 26, 2019.

  1. Welder Dave

    Welder Dave Senior Member

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    Has anyone came across NPT pipe plugs using a metric allen key? I have aftermarket rollers and need to add oil to one but the standard 3/16" allen key is too small. I got a 5mm allen key to try that is a little bigger but just wondering if anyone has come across this. I did read that that they can come with a 5mm hex but don't know how common they are.
     
  2. ih100

    ih100 Senior Member

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    Came across the exact same size just a couple of weeks ago. It was a first for me as well, I thought I’d got my sets of Allen keys mixed up.
     
  3. funwithfuel

    funwithfuel Senior Member

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    If you take a thread gauge to the fitting when you get it out, I think you'll be surprised. For example 1/8 NPT has 27 TPI but 1/8 BSPT is the same diameter but has 28 TPI. Its really hard to tell them apart, even with a thread gauge.
     
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  4. excavator

    excavator Senior Member

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    I've seen broken housings when people don't know this and try to put a NPT in place of a BSPT.
     
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  5. Welder Dave

    Welder Dave Senior Member

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    Success! I went out today to see if I could get the plug out. I smacked it a couple times with a center punch and then tapped the 5mm hex key in. It was a snug fit and the plug came out without too much trouble. Now just to get the 00 grease and fill it up... and wait for the weather to smarten up so I can do something. -2C with a strong wind that goes right through you. Glad I put up the pole shed a few years ago. Just being out of the weather makes a huge difference.
     
    Ronsii likes this.