Hand tools for chamfering plastic pvc pipe
This video shows the various hand tools that people use to chamfer plastic pipe. The video first discusses he reason for chamfering plastic pipe before cementing it into fittings. Many people think that the reason is so that the pipe fits into the socket easier, but in fact it the primary reason, is so that the glue is not scraped off the socket but the sharp edge of the pipe.
A surform is a very poor way of chamfering PVC and ABS pipe as it is far too coarse and will chip the pipe, leaving a ragged edge, rather than a nice smooth chamfer.
A metal file (crosscut) is often the preferred method of many pipe fitters for small diameter pipes - 63mm and below. A scraper is another option, although this is not good for pipes below 40mm as it is hard to control. Scrapers are very good for larger diameter pipes.
A small hand grinder with a zirconium flapper disc is an excellent tool for chamfering larger diameter abs and pvc pipe ends. This tool can quickly put a good, even, smooth chamfer on plastic pipes as large as 12" (315mm).
Our engineers tend to have all three tools, the file, scraper and zirconium flapper disc on their toolboxes at all times. This way they know they can properly chamfer almost any plastic pipe they come across.
If making a repair, the ABS and PVC pipe can be in a very awkward position and the normal first tool of choice may be limited due to space. It is therefore essential to have a range of tools in your box, so that repairs can be quickly carried out.
How to select the right type of ball valve for a pvc pipe system
Selecting the right ball valve for a plastic pipe system can be critical. In this video, we explain how to decide whether a single or double union ball valve should be used.
In most applications, a double union ball valve is the most appropriate valve to use. The advantage of a double union ball valve is the valve body can be completely separated from the pipeline, even if the pipeline is fixed either side. This allows for the valve to be inspected for blockages, seals to be checked, cleaned and replaced and then put back into service very rapidly. To perform the same with a single union ball valve, would require the pipe to be cut, as only one side of the valve can be removed using the union nut.To refit the valve a socket will have to be glued inline. This will mean that the system needs to be down for many hours, whilst the cement dries.
Single union ball valves are only really of use at the end of a pipeline, where there is nothing attached or permanently fixed, to the other end. Such situations include the ends of scour lines and drain lines or entry into an open tank or other vessel.
Ball valves are the lowest cost of any type of valve used in plastic pipe systems. They are very good where you need either a fully open of fully closed valve. When fully open they run at full bore, with very little headloss or restriction, making them very energy efficient. The nature of the ball however, combined with only a 90 degree turn of the handle between fully closed and fully open, makes flow control, using a partially open valve, very difficult to accurately set. Applications where a control of the flow rate is required is best served by either our fine control gate valves or diaphragm valves.
New film studio!
Customer service comes first at PlasticPipe Shop Ltd., and we have recently invested in a new film studio facility, in
order to create high quality and informative videos about the plastic pipe
systems we supply.
The videos are to be posted in
the relevant sections on our website as well as on our own You Tube channel PlasticPipeShopTV.
Making the move from pipe
technician to movie director, and ecommerce to acting has been a new experience
for us all here! After several interruptions by trucks reversing outside, dogs
barking and people coming into the room unannounced, we finally worked out that
we are best recording these plastic pipe videos in the middle of the night when
the rest of the country is asleep. So if we look a little bleary eyed in some
of them, it is not because we have been out burning the midnight oil the night
before, but probably because we are still burning it whilst recording! After,
admittedly, trying to do it on the cheap using webcams and other low cost
recording equipment, we decided that grainy images and muffled voiced weren’t
up to scratch, so after a lot of investigation, we find ourselves now experts
in video equipment as well as plastic pipe!
Our first video on the
differences between single union and double union plastic ball valves was
uploaded a week or so ago, and since then we have recorded three more; a “how
to” on chamfering pipe and tow product videos on fine control gate valves and valterra
slide valve.
The plan is for all of use to
have a shot in front of the camera so that you, our customers can get to see
our ugly mugs and put a face to a name when you are speaking to us about plastic pipe fittings on the
phone.
Do’s and Don’t’s for cementing plastic pipe systems
Do’s and Don’t’s for cementing plastic pipe
systems
·
Do chamfer the edges of a cut
pipe. Chamfering is not, as many incorrectly believe, a process that enables
the pipe and fitting to glide together more easily, although this can be an
added benefit. The main purpose of chamfering the outside edge of a pipe before
the application of cement is to allow as much of the cement as possible to
enter the joint. A straight cut pipe without any chamfering will act as a
blade, scraping off the solvent cement inside the socket.
·
Do use additional unions to
make the process pipework easy to disassemble in the future. Although it is
often difficult to imagine why a system might need to be taken apart, unions
should still be added for good practice. A pipeline may require to be
inspected, cleaned or modified, and if unions are installed then these
processes become easier, reducing downtime in the future.
·
Although not always possible,
do try to leave a short section of pipe between each fitting rather than
butting them up right next to each other. A section of plastic pipe between the
fittings should be a little longer then a socket depth for that size of pipe.
Following this rule allows far easier adaptation of the pipework in the future,
as a fitting can be cut out, leaving a spigot long enough to cement another one
on.
·
Do work out where your last
join will be about five or six joins before you get to it, and ensure there
will be enough movement available to make the joint. It is often the case that
inexperienced fitters get to the last join and realise it is to a wall
connection or other immovable object, and there is not sufficient space to
allow for the socket to be pushed on to the pipe. In such situations a remedy
is to fit a short section of plastic pipe, with a union at either end, so that
it can be removed to give movement to the plastic pipe system.
·
Don’t add cleaner to your
cement to try to thin it down after leaving the led off for an extended period.
This will result in a poorly performing and potentially leaking, joint.
Whenever possible rest the lid of the cement tin back on top to prevent
evaporation of the solvent. If the solvent cement becomes too thick to apply or
lumpy, it should be discarded and a new tin opened.
Finally, remember that shortcuts taken when
assembling plastic pipe system always bite back in the end!Common errors made when cementing plastic pipe systems
Common errors made when cementing plastic pipe
systems
ABS, CPVC and
PVC pipes and fittings are generally connected to each other using a solvent
weld process. After cleaning the pipe and fitting of any grease or dirt, a thin
film of solvent cement is painted onto both surfaces and they are pushed
together in one swift movement. The solvent cement melts a thin layer of
plastic on the pipe and fitting and as the solvent evaporates, these layers
fuse together to form a strong seal. This would appear to be a straight forward
process. Like many such processes however, there are a few do’s and don’ts that
need to be followed;
·
Don’t paint the solvent cement
on to the pipe first. The socket should be coated first and then the pipe. This
is because the socket can be put down on a surface whilst the pipe is painted.
If the pipe were painted first, it is difficult to put it down anywhere without
getting grit and dirt on the cement.
·
Don’t let solvent cement or
cleaner run into a valve. If at all possible unscrew the unions, or remove the
flanges from the valve, glue into position and then, once the cement has
dried,, reassemble the valve. Care must be taken to ensure the union nuts or
flange rings are on the pipe before cementing the fitting. If the valve must
remain assembled, apply the cleaner / cement to one side of the valve and sit
it vertically with the cemented socket facing downward whilst you apply cement
to the pipe. Push the valve downwards onto the pipe and leave to set in this
position. If it is suspected that cement may have entered the valve body, turn
the handle a few times to ensure the mechanism remains free. In the case of an
abs valve, this must be done very quickly as the setting rate for abs is very
much faster than pvc pipe.
·
Don’t twist or turn the PlasticPipe Fittings together as they are assembled. The error is often made by
inexperienced workers, who believe that it will ensure the cement is spread
throughout and give a better join. What in fact happens, especially with ABS
pipe and fittings (as the y set much quicker) is that the moment the two
surfaces come in to contact with each other, the solvents begin to melt the
plastic surfaces and they begin to fuse together. Twisting the pipe / fitting
tears the newly formed, fused layer and prevents it from forming correctly.
This will result in a leaking joint.
Electrically Actuated Plastic Valves
Electrically Actuated Plastic Valves
Electrically
actuated valves are an increasing requirement for plastic pipe systems, due to demands for electrical efficiency and
24/7 system operation.
Types of electrically actuated valves
Electrically
actuated valves are available in three standard configurations;
·
Open / close
o
Power source is required to
open and close the valve e.g. when power is applied to terminal 1 and
taken away from terminal 2 the valve will open and the opposite will occur when
the power is switched across. Open / close type valves are suitable for
automated filling and emptying of tanks, reservoirs. They are also very useful
in fully automated processes like backwashing filters and priming pump supply
lines prior to an automated pump staring. Open / close type valves are often
used at the end of plastic pipe lines, where a line is required to be purged
before refilling once a pump starts.
·
Spring Return
o
These are available in either a
normally open or normally closed configuration. When normally open the plastic
valve will, with the aid of a powerful internal spring, return to the open
position when the power is removed. When normally closed, the valve will close
when the power is removed. Spring return valves are often used for emergency
supply lines, where, in the event of power failure a bypass needs to be opened,
a line needs to be drained or a tank needs to be filled or drained.
·
Modulating
o
Modulating valves have the
power constantly applied to them and have an additional controlled power source
of 0-10volts dc or 4-20mA. The controlled power source is supplied by a
controller that is usually responding to input from a sensor, such a s a
pressure or flow sensor. The controlled power source partially opens and closes
the valve to give a controlled flow. The accuracy of a modulating valve will
only ever be as good as that of the sensor and controller.
Modulating valves are excellent at controlling tank levels by using
feedback from either a level sensor or a sensitive, submerged pressure sensor.
Other applications include controlling the pressure in a supply line, although
this is more often done using an inverter (speed controller) if it is a 3 phase
pump that is supplying the line.
Technical Bulletin: Plastic pipe threaded fittings
1. Thread types
Plastic pipe
systems such as PVC and ABS have the advantage of being able to be quickly and
easily assembled, using solvent cement that is painted on the pipe and socket.
There may however be occasions when a threaded fitting is required. Such a
situation often occurs when connecting to pumps or other equipment or when
transitioning from one material to another (such as plastic to metal).
BSP Threads
Nearly all
metric and most European made imperial threaded pvc pipe fittings, have a BSP
Parallel thread on them. The “BSP” denotes that the set and depth of the thread
conform to “British Standard Pipe” thread. An additional “P” is often used as a
suffix (BSPP), to denote the thread is a parallel one rather than a tapered
one. Additional suffixes of either “M” or “F” are also sometimes used. These
denote whether the thread is a male (i.e. thread on the outside) or female
(i.e. thread on the inside) fittings.
NPT Threads
Apart from BSP,
the other commonly found thread in plastic pipe systems is NPT, an American
standard (National Pipe Taper), which is only usually found on plastic pipe
parts that originate in the USA.
Comparison of BSPP and NPT threads
BSPP and NPT
threads are generally not compatible. The first hurdle we come to is that one
is parallel and the other tapered (a tapered thread is a conical shape, whereas
a parallel is the same diameter all the way along). As such, even if the pitch
and thread depth were the same, a male parallel will only go into a female
tapered by a single thread and will not be secure. A male taper will usually go
into a female parallel about 40-50% of the way and can, as long as a thread
sealant is correctly used, be regarded as being generally secure.
|
Pipe
Size
|
Pitch
(Threads/Inch)
|
|
|
NPT/NPS
|
BSP
|
|
|
1/16"
|
27
|
---
|
|
1/8"
|
27
|
28
|
|
1/4"
|
18
|
19
|
|
3/8"
|
18
|
19
|
|
1/2"
|
14
|
14
|
|
5/8"
|
---
|
14
|
|
3/4"
|
14
|
14
|
|
1"
|
11 1/2
|
11
|
|
1 1/4"
|
11 1/2
|
11
|
|
1 1/2"
|
11 1/2
|
11
|
|
2"
|
11 1/2
|
11
|
|
2 1/2"
|
8
|
11
|
|
3"
|
8
|
11
|
|
3 1/2"
|
8
|
11
|
|
4"
|
8
|
11
|
|
5"
|
8
|
11
|
|
6"
|
8
|
11
|
|
8"
|
8
|
---
|
The above table gives the pitch (the number
of threads per inch) of NPT and BSPP threads. As can be seen, the only two
sizes that are compatible are ½” and ¾”. All other sizes have different pitches
and so will thread together. The ½” and ¾” sizes will connect, but only if the
male part is NPT and the female is BSPP, and then only expect the thread to
insert to about 40-50% of the whole thread.
Connecting
different thread types
The preferred option to connect different
thread types is to use one or more adaptor fittings. For example if it is
required to connect a 1” BSPPM (male) to a 1” NPTF (female), the correct method
would be to us a 1” BSPPF : Plain socket, and a 1” NPTM : Plain nipple. This
would extend the length of the fitting, which in some cases may cause issues,
however it ensures that a system is correctly fitted, and suitable for its
design pressure specification.
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