Wiping Joints on Lead Pipes
Plumbers make joints in lead pipes with soft solder which, by means of
cloths, they “wipe” to the shape shown by Fig. 47.
Figs. 46 and 47 show the difference between a copper-bit or blowpipe
joint and a wiped joint.
=Plumbers’ Solder.=--As already stated, coarse, or plumbers’ wiping
solder, is made in the proportion of 2 of lead to 1 of block tin. Care
must be taken that the lead is quite pure and free from any other metal,
as zinc-adulterated solder will be difficult to use, and joints made
with it on service pipes will not be sound. In melting up scrap lead for
making solder, only sheet lead should be used, as the lead used in the
manufacture of sheets is much purer and contains a greater proportion of
pure pig lead. The scraps must be quite dry; a damp piece dropped into a
pot of molten metal may cause a serious accident, as the contents of the
pot may be blown out.
To test the quality of solder when made, heat it as for wiping a joint;
the correct temperature is determined by dropping a small piece of
newspaper into the pot, and if it quickly burns and catches alight the
solder is right for using. Next pour a small quantity on to a cold but
dry stone or cement floor. This, on cooling, should have a few spots on
the surface about the size of a threepenny-piece, and on the under side
should be bright nearly all over. Solder of this quality would, if
properly used, stand any pressure without sweating. If the solder on the
stone or cement floor looks white on both sides, or has a few small
bright spots on the under side only, it is too coarse and requires more
tin. On no account should the solder be heated to redness, as the tin
rises to the top and quickly turns to dross (see p. 11). If this should
happen to solder that is being used for service pipes, it should be
rectified by adding more tin.
[Illustration: Fig. 46 Fig. 47
Fig. 46.--Copper-bit Joint on Lead Pipe
Fig. 47.--Wiped Joint on Lead Pipe]
To purify a pot of “poisoned” solder (solder that contains zinc), melt,
stir in a handful of common sulphur or powdered brimstone until the mass
is of the constituency of wet sand, heat to the ordinary working
temperature, and carefully remove the crust that forms on the top, and
the solder will then be fit for use, except that a little tin must be
added to it. The presence of zinc in solder can be detected by the
difficulty of forming joints, the metal falling apart and working very
lumpy, and the joints when finished having a dirty grey appearance.
When plumbers’ solder is bought ready for use from the manufacturers, it
is usually in the form of casts of eight bars, weighing about 56 lb. to
the cast. The best only should be used, as cheap solder is frequently
the cause of much trouble if used on high-pressure work, and joints made
with it are never of good appearance. To test manufacturers’ solder,
wipe a joint with it, and if it is of good quality it will work easily
at a good heat, and when cleaned off with tallow and a clean rag it
should be well covered with bright spots.
Brass fittings should not be tinned by dipping into the solder pot, as
brass being an alloy of zinc and copper, the zinc may be melted into the
pot with disastrous results.
=Flux.=--The flux used is tallow, no other flux answering the purpose so
well, although mutton fat has been used as a substitute. Plumbers often
call tallow “touch,” and they frequently use it in the form of tallow
candles, the cotton wicks coming in handy for packing spindles of taps
and slides of gas pendants.
An excellent plumbers’ black, soil or smudge, can be bought in packets,
and requires only to be mixed with water before using. Ordinary black
consists of lampblack, glue, and water. The black should be first mixed
with water, afterwards adding the glue, which must have been previously
melted in a glue-pot. Simmer this for a time to remove surplus water.
Test the black on a piece of sheet lead and dry off slowly. If it chips,
add more black, but if it rubs off add glue.
The black should be made in small quantities, as it deteriorates if
kept.
[Illustration: Fig. 48.--Joints prepared for Jointing]
[Illustration: Fig. 49.--Marking-gauge for use on Pipe Ends]
Another recipe is to place in the pot 1/4 lb. of size or diluted molten
glue and a little water; gently warm until the size dissolves, but do
not boil. Mix 1/2 cub. in. of chalk ground to a fine powder with a
pennyworth of lampblack, and then with a pallet knife incorporate some
of the melted size with the mixture on a flat board or stone to form a
thin paste, after which place the whole in the pot, warm, and stir
together thoroughly. Test as before. Old and thick soil is thinned with
porter or stout, but do not add too much or the soil will become so
sticky that the solder will cling to it. A little brown sugar, or a
little stout, added to the black will make it more tenacious, and cause
it to dry with a slightly glossy surface. Some plumbers soil their
joints after they are made, with black japan or thinned Brunswick black.
But it is doubtful whether the effect is so good as when a “dead” black,
such as given by ordinary soil, is used.
=The Cloths.=--Solder cloths for underhand joints should be from 1/2 in.
to 7/8 in. wider than the joint for which they are to be used, and about
1/2 in. longer than they are wide. Most plumbers use the same cloths for
underhand and upright, but it is preferable to use a special cloth for
4-in. upright joints with the length 1 in. less than the width. For
getting up the heat of an underhand joint on a small pipe a larger cloth
may be used until the worker is sufficiently skilled in joint wiping not
to burn his fingers when using the correct size. For 3-in. joints and
upwards a large cloth must be used first to get up the heat, the wiping
cloth being kept warmed and ready for use when the heat is right. This
large cloth, as used by some plumbers, is often long enough to lay on
the worker’s arm, but this is clumsy to use when the joint to be wiped
is in a cramped position, and is liable to let the pipe get burnt, as
the metal it holds cannot be readily distributed round the joint; 8 in.
by 9 in. is a good size to practise with on the bench, and as more skill
is obtained it can be reduced to 7 in. by 7 in. A diagonal strap should
be stitched to the back to take the little finger and thumb; the
position for this can be obtained by laying the cloth face downwards and
placing the hand on it with the finger slightly spread; the wrist should
be over the right-hand corner, so that when the cloth is being used the
edge is readily kept parallel with the sides of the pipe. Branch cloths
are made from 1-1/2 in. to 2-1/2 in. wide and about half as long again
in width. These cloths should be about seven thicknesses of material,
all others being nine or ten.
White moleskin cloth is obtained from the tailor’s for making these
solder cloths, is usually 1 yd. wide, and costs about 3s. per square
yard. The usual method of making cloths is to cut a strip down the
selvedge of the material and fold up the strip till the desired size is
obtained; it can then be cut off the piece, and any odd ends left may be
used for packing a larger cloth. Another method is to cut a square piece
the required size, and then fold it three times each way. This makes a
rather clumsy cloth for small sizes, but makes a very good “blanket.”
=Horizontal or Underhand Joints.=--For making a successful wiped joint,
the ends to be joined must be a good fit and the temporary fixing must
be sufficiently strong so that the joints will not be broken in the
process of wiping. These two points should be always strictly attended
to. Service pipes should be tightly pressed home one in the other, the
cupped or female end shaved inside with a knife, but not close in as is
the case with soil or waste pipe; this allows the solder to fill up the
cavity, which effectually prevents any tendency to sweat. This principle
is followed up by some plumbers with branch joints on small size service
pipes, the male end being worked in with a twisting motion, to prevent
any solder getting into the pipes. All other pipe joints should be
closed, the female end being tightly worked in round the male end of
pipes as an extra precaution against the solder getting inside. It is a
good plan to black the inside of waste and soil pipes, so that the
solder will not adhere if any should get through when making the joint.
Fig. 50 shows the wiping of an underhand joint.
Beginners often spend a lot of time practising “rolling” underhand
joints. This is bad practice, and will be of no use in wiping fixed
joints. Little advice can be offered with regard to the actual wiping,
constant practice being the essential thing. See that the solder is at
the correct heat. This is readily found by dropping a piece of newspaper
into the pot, and, if it quickly browns, the solder is ready for use. If
the solder is used too hot it will quickly burn holes in the pipe, and
if not hot enough a heat cannot be properly worked up, and the cloth may
get torn trying to move hard metal. For underhand joints pour on
steadily with a circular motion on to the sides of the joint, and on to
the soil at the ends of the joint, until sufficient solder in a molten
condition can be brought up to cover the top of the joint with the
cloth, which is held underneath it; then pour steadily all over the
solder until it runs back again. Repeat this continuously until the
solder can be worked in a substantial body all round the joint without
any hard solder being left at the underneath edges. Give the joint a
last pour on, and wash all the solder into the cloth. Bring the solder
smartly on to the top, and quickly work it all round the joint with the
wiping cloth, using two fingers of one hand for the top and back edges,
and the index fingers of both hands for the underneath part. The top of
the joint should be roughly shaped first and the surplus metal brought
over the back to the underneath; this should be worked into the bottom
of the joint with a slight sideways motion. The extra body of metal
should be used to warm up any hard edges, the surplus being brought up
again to the top and quickly thrown off to the back.
[Illustration: Fig. 50.--Pipes Supported and Secured on Bench for Joint
Wiping]
[Illustration: Fig. 51.--Finished Wiped Joint]
=Upright Joints.=--These are more trying to the worker’s patience but
are the easier to wipe. After the pipe has been fixed in position, a
lead collar should be fixed a few inches below the joint to catch the
surplus metal. A piece of stout string tied by a half hitch round the
pipe will prevent any leakage of the solder. In working up the heat of
an upright joint, care should be taken to work steadily round the joint
so that the heat is the same throughout. After sufficient metal has been
splashed on with the splash stick and ladle, and the metal is at a
moving heat, roughly shape up the joint with the splash stick, keeping
the metal fairly high on the joint; then splash on a little more hot
metal all round. A warm cloth is now used to shape up the joint by
bringing the lower metal up to the higher part, after which start to
wipe first with the hand as far round the back of the joint as possible
and bring the surplus metal to the front, the cloth being held by the
thumb and the index and little fingers; then change the cloth to the
left hand and repeat the operation. The joint should be finished off at
the back, although if quickly done the finish off should not be
apparent. The collar must now be taken off and the solder it contains
melted with a plumber’s iron.
A plumber’s iron can be used to good purpose on these joints, especially
if they are out of doors and the weather is rough. The iron must be
heated to redness and well filed up.
[Illustration: Fig 52.--Making Upright Wiped Joint]
[Illustration: Fig. 53.--Wooden Collar or Platform to Catch Waste
Solder]
[Illustration: Fig. 54.--Lead Collar to Catch Waste Solder]
[Illustration: Fig. 55.--Pipes fully prepared for Jointing]
Where possible, all joints to be wiped in their permanent position are
sprung away from the wall and temporarily fixed with steel points made
from 1/2-in. hexagon steel about 9 in. long and drawn out to a point at
one end. In some cases, more particularly soil-pipe work, the pipes
cannot be fixed away from the wall; a hole must then be cut into the
wall about 4 in. back and about 12 in. square to allow the joint to be
properly made at the back.
=Wiped Joint between Lead and Cast-iron Pipes.=--In wiping a lead pipe
to a cast-iron pipe perhaps the best practice is to file clean the end
of the cast-iron pipe first and then coat with pure tin, sal-ammoniac
being used as a flux. The pipe then is washed to remove the
sal-ammoniac, and afterwards “retinned,” using resin and grease as a
flux. A plumber’s joint then is wiped in the usual way. It is necessary
to take great pains to make a good sound strong joint between the two
metals, but even then in the course of time (it may be only a few years)
the iron will come out of the solder. The first sign of decay will be a
red ring of iron rust showing at the end of the joint. This rust will
swell a little and cause the end of the soldering to slightly curl
outwards. Eventually the rust will creep between the solder and the iron
and destroy the adhesion of the one to the other. The joint would
eventually become a loose ring on the iron pipe, but not on the lead
pipe, as the expansion of lead and solder do not differ to any great
extent. Only those metals that alloy together can be satisfactorily
joined by soft soldering, and the solder should contain as great a
proportion as possible of the metals to be united.
The illustrations to this chapter (Figs. 46 to 55) are
self-explanatory.