5/8th tap washer not 5/8ths in diameter!?

eveares

eveares

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I bought some replacement 5/8 tap washers from screwfix, however they are larger than 5/8ths of in Inch in diameter!

What tap washers do I need for my bathrooms sink tap, the old washers are 5/8ths in overall diameter.

Regards: Elliott.
 
Never heard of 5/8 washers - and screwfix list only "Pegler 1/2 inch" and "Holdtite 3/4 inch":unsure:
 
Why not reduce the diameter of the over size washer :?:.

Hopefully the tap is worth the effort ie has no other defects :idea:
 
Couple of comments from the Screwfix user comments on the 5/8" washer
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" The product looks like any other tap washer, and will no doubt do the job fine.
However the sizing system seems completely bonkers!
I measure the diameter of the washer that needs replacing - its 5/8" - then find the 5/8" washer in your catalogue. Check the specification - yes, it says 5/8" diameter - and order. The product is embossed 5/8", but what is its diameter? Over 3/4"!
I then have to change it for one stamped 3/8", which is actually about the 5/8" I require.
How crazy is that! "
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" Re: size confusion - taps use BSP size references. To get the BSP size measure the outside diameter and then subtract 1/4". So a washer that measures 5/8" is a 3/8" BSP washer (5/8 - 2/8). Helps if your are pre-decimal vintage but not much when it comes to BSP ! "
 
I know this is an old post but as it turns up high on google I'm going to post a response.

The OP asks why is 5/8 washer is actually 22mm. He could have asked why the 3/8 tap washer is actually 5/8. Or he could have asked why a host of other pipework is not actually the size stated.

Why is this? No one knows but it's prevalent in plumbing. My guess is that plumbers don't have rulers so they originally mislabelled parts and no one has ever corrected them.

What is more worrying is that when this valid question is asked, the responses are completely ignorant of the issue and respond with get in a professional. FFS it's a tap washer, he doesn't need a plumber, he just needs an explanation.
 
The plumbing and heating industry often use the term "nominal size" and it's very different to the actual measured size.
 
1. The key to plumbing sizes is the use of British Standard Pipe (BSP) threads.
2. The size of the threads relates to the internal bore of a particular pipe size. Thus 1/2" BSP relates to a steel pipe (barrel!) with an internal diameter of 1/2". Similarly 3/4" BSP relates to pipe with an internal diameter of 3/4".
3. The outside diameter of a pipe with a (nominal) internal diameter of 1/2" will be 1/2" plus twice the wall thickness of the pipe.
4. A 1/2" BSP pipe will have an outside diameter of about 0.8 inches. So the male thread will read 0.8" across the crests. Of course, without an accurate measure, this looks like 3/4"!
5. When metrication came in, and people stopped learning Imperial sizes at school, it became almost alien to many.
6. This standard may sound crazy now, but was a perfectly useful and adequate system in the past.
7. Most taps which have threaded shanks are 3/4 BSP (bath taps) or 1/2" BSP (basin taps).
8. If anyone would like a more complicated life, then BSP comes in two flavours, tapered threads (BSPT) and parallel threads (BSPP). The major and minor diameters of male and female threads differ between the two.
 
Simples; they are washers for 3/8 tap. Size relates to the tap size and not the washer. The common misconception in plumbing relates to BSP sizes, which are standard pipe sizes referring to the internal diameter of said pipe. BSP threads can also be parallel or taper, just to confuse you. Compression fittings on copper pipe refer to the pipe OD and oldones are imperial, newer ones metric. I'm sure all trades have their idiosyncrasies, not just plumbing, which is why tradesmen exist.
Crossed with Old Buffer
 
bikeman123 said:
I know this is an old post but as it turns up high on google I'm going to post a response.

The OP asks why is 5/8 washer is actually 22mm. He could have asked why the 3/8 tap washer is actually 5/8. Or he could have asked why a host of other pipework is not actually the size stated.

Why is this? No one knows but it's prevalent in plumbing. My guess is that plumbers don't have rulers so they originally mislabelled parts and no one has ever corrected them.

What is more worrying is that when this valid question is asked, the responses are completely ignorant of the issue and respond with get in a professional. FFS it's a tap washer, he doesn't need a plumber, he just needs an explanation.
Click to expand...
Given that this was over two years ago, I suspect they've either found a new washer, replaced the tap, or moved house by now
 
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