At certain sizes, NPT and BSP share the same number of threads per inch - at ½" and ¾" - but at all other sizes the two are quite different. The table below lists the TPI for both NPT and BSP at sizes commonly used with domestic radiators. Nominal One of the main advantages of using millimeters over inches is the increased accuracy and precision. Millimeters are a smaller unit of measurement, allowing for more precise calculations and measurements. This is particularly important in industries where even the slightest deviation can have significant consequences, such as in the manufacturing of electronic components or the construction of intricate machinery. The nominal size refers not to the outside of the pipe, nor even to the outside of the thread, but to its internal bore - the inside of the tube where the fluid flows. It makes sense when sizing pipes for flow rate but it makes things confusing when measuring for replacement parts. And the 15mm:3/8" male:female adapter (labelled [2] in the attached) was called " 15mm x 3/8" Compression Female Adapter" I've drawn a diagram (attached) which shows the current set-up and the two incorrect parts I have (which could become part of the solution, if necessary). I've colour-coded blue as 15mm, red as 3/8".

British Standard Pipe is the standard thread used on plumbing fittings across most of the world (but not in North America). Below, you'll find tables showing BSP sizes in mm; tables detailing the difference between BSP and the American standard NPT; an explanation of straight and tapered thread types; and a handy thread size ruler and template to print out and use at home.Essentially the issue is that I have a new monobloc tap (Grohe Ambi monobloc chrome) which I'm having trouble connecting. The copper from mains ends with a male threaded 15mm connection, and the tap flexible pipe ends with a 3/8" female connection. G is the international standard shorthand for BSPP - BSP Parallel threads. R is the standard for BSPT - BSP Tapered. Parallel (G) threads are used where the seal is made on a mating face, like inside a cast iron radiator with the aid of a gasket. Tapered fittings achieve a tight thread-to-thread seal with the help of a little sealant such as PTFE tape or hemp and Boss White. Right first time An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot. The inch is usually the universal unit of measurement in the United States, and is widely used in the United Kingdom, and Canada, despite the introduction of metric to the latter two in the 1960s and 1970s, respectively. The inch is still commonly used informally, although somewhat less, in other Commonwealth nations such as Australia; an example being the long standing tradition of measuring the height of newborn children in inches rather than centimetres. The international inch is defined to be equal to 25.4 millimeters. A millimetre (American spelling: millimeter, symbol mm) is one thousandth of a metre, which is the International System of Units (SI) base unit of length. The millimetre is part of a metric system. A corresponding unit of area is the square millimetre and a corresponding unit of volume is the cubic millimetre.

If you want to convert another length or height in inches to millimeters than 3/8″ to mm use our inches to mm calculator. So the 15mm:3/8" male:male adapter (labelled [1] in the attached) was called " 15mm Compression by 3/8" BSP Male Iron Thread European Flexible Tap Adapters (Pair)" NPT - National Pipe Thread - is the US standard. Most of the rest of the world uses BSP - British Standard Pipe. Apart from 3/8 inch in mm you may also be interested in the other units of length in the International System of Units: Converting inches to millimeters is a common practice in various fields, including engineering, manufacturing, construction, and design. The primary reason for this conversion is the need for precise and standardized measurements. Millimeters are a metric unit of length, widely used in most countries around the world, while inches are an imperial unit primarily used in the United States and a few other countries.In brief: products for sale in the UK and Europe ship with BSP threads; products that we export to North America are fitted with NPT threads. NPT has flattened peaks and troughs where BSP is rounded. NPT has a thread angle of 60º where BSP is 55º.

Millimeters are widely used in various fields, including engineering, manufacturing, and construction. They provide a precise and accurate measurement for tasks that require fine details. For example, in the field of machining, millimeters are used to measure the dimensions of components with high precision, ensuring a perfect fit and functionality. Below is a summary of the common BSP thread sizes in used with cast iron radiators and their corresponding actual outside diameters in millimetres. The actual outside diameter is what you can measure when looking at a valve tail, a threaded nipple, reducing bush or an opening in the radiator. BSP Sizes In Millimetres Nominal At the same time I'm not proficient enough to carry out any solution that involves cutting copper or soldering etc