Seeking help regarding thread connection methods and classifications

This post was last edited by ylb913 on 2016-8-13 09:14. American standard generally sealed tapered threads: NPT (taper of 1:16). Generally sealed pipe threads: R (taper of 1:16). Codes for British standard sealed external tapered threads: R1 – used in combination with British standard sealed internal cylindrical threads; R2 – used in combination with British standard sealed internal tapered threads. Code for British standard sealed internal cylindrical threads: Rp. Code for British standard sealed internal tapered threads: Rc

It means R1 is used in combination with Rp, and R2 is used in combination with Rc! So, can the internal and external threads of a standard sealed pipe thread R be used together directly? Also, can these thread types be used in combination with those indicated by M...X... (such as M10X65)?

This post was last edited by ylb913 on 2016-8-13 at 13:19. That term \"general sealing pipe thread R\" is an umbrella term that includes combinations of R1 with Rp, and R2 with Rc. I have never seen threads expressed in the format like M10X65.

This post was last edited by zhangjuhua on 2016-8-14 10:51. M10X65 – is 65 the total length of the thread? I have seen M10X1.5,2; the number that follows indicates the pitch. The pitch and thread profile must match those of the matching screw in order for them to fit together

Yes, this is the common way of indicating bolt length. For example, a nut of the type M16x85 can it be connected to a fitting of the same specification?

Nut? It’s clear what the pitch of this type is; by default it’s probably 1.5 for coarse threads, and also the thread profile – is it the same? If so, there should be no problem

This post was last edited by Pinocchio on 2016-8-16 09:41. M16x85 is likely the specification for a metric coarse-threaded bolt or stud, with the dimension 85 referring to the length of the bolt or stud. Metric threads (thread code M) are used only for connection, not for sealing; the thread standard is GB/T 196-2003. Metric threads can only be connected to other metric threads; they cannot be connected to threads of different types. The thread diameter and pitch vary. The GB thread standards used for sealing are as follows: 1. GB/T 7306.1-2000 \"55° seal – circular internal thread + conical external thread\", with a corresponding thread code; 2. GB/T 7306.2-2000 \"55° seal – conical internal thread + conical external thread\", also with a corresponding thread code. These two standards are equivalently based on ISO 7-1:1994 \"Pipe threads sealed with threads\". 2. GB/T 12716-2002 \"Sealed pipe threads at 60°\", thread codes, which are equivalently adopted from ASME B1.20.1:1983 \"Sealed pipe threads\". 3. GB/T 7307-2001 \"55° Unsealed Pipe Threads\" – thread codes, which are equivalently based on ISO228-1:1994 \"Pipe Threads Without Thread Sealing\". Although it is a \"non-sealed\" standard, the use of sealing materials such as tape can still enable sealing at normal temperature and low pressure; for example, the threaded connections in tap water pipes use G threads.

Thank you so much! ! ! I got it this time!

Standards should be treated as standards! It’s essential to know where they are to be used, and to apply theory in practice... Threads can be divided into two categories: 1. 55-degree type； 2. 60-degree type ； Each type can be further divided into straight thread and tapered thread ； One uses pitch and the other uses the number of teeth! Since it’s a thread, there is an inner side and an outer side… Imagine three different types of fits: straight-to-straight fit, straight-to-tapered fit, and tapered-to-tapered fit! Straight-to-straight fits are generally used only for connection and fastening; tapered fits are used not only for connection and fastening but also for sealing purposes! Common metric sealing threads usually require additional sealing materials such as tape or graphite on-site in order to achieve a seal ； Secondly, British-style sealed threads such as NPT achieve sealing simply through dry thread sealing! As for which one to use, it depends on the standards: the standard metric system is generally based on European standards, while the imperial system is based on American standards!

Since I work in the petrochemical industry, I may be more familiar with pipe threads; the above is merely my own summary. Other types of threads, such as those at 45 degrees, with different tooth shapes, round or square threads, etc., are not covered in detail here – as they are used less frequently, so there is less information available on them…