Page 120 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

2 Whiteheart fittings with parallel female threads are identified by a rounded
bead around the mouth of the fittings. These fittings are slightly softer, and
therefore more flexible, and tend to stretch if over-tightened.
 Table 2.24

Couplings Equal tees Elbows M/F elbows

Unions Nipples Bushes

When cutting a thread onto a length of pipe, the length of the thread should be
such that, once the joint is made, one and a half to two threads should be visible
when the joint is completed.
There are a variety of jointing compounds that can be used with threaded joints.
Jointing compounds are used to make leak-free joints. Each one has a specific
use, although some are universal and can be used on a number of different
installations. Jointing compounds include those listed in Table 2.25.

 Table 2.25 Jointing compounds
Linseed oil-based compounds (boss white, Can be used in conjunction with hemp on
hawk white and templars paste) wet central heating systems and compressed
air lines. Must not be used on natural gas
installations.
Unsintered polytetraflourethylene (PTFE A thin, white (or yellow if used on gas) tape
tape) that can be used on most installations,
including hot and cold water, central heating
and gas installations.
PTFE-based jointing compounds (boss A compound specially made for use on hot
green) and cold water supplies. Not suitable for
natural gas installations.
Hematite paste A truly universal compound that can be
used on many installation types, such as
oil, gas, hot and cold water, central heating,
compressed air lines and vacuum lines.
Manganese paste These are specialist compounds for use
Graphite paste with high temperature hot water and steam
installations.
Gas seal paste A specialist compound for use with natural
and liquid petroleum gas installations.

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