Since this video is all about tube bending, we thought it would be fun to create a little
challenge to go along with it. We asked three different people — all with different levels
of experience with tube bending — to connect two fittings on this high pressure control
valve package.
This is usually just eyeballed. Go with it. A little bit of a twist.
Oh, ok, it's rounded over here. So maybe this is where you bend it.
We’ll show you the results to our challenge in an upcoming video, so be on the lookout.
Whether you're an experienced technician or a beginner, this video will provide you with
useful information about fittings and the basics of using a hand tube bender for pneumatic
devices in the oil and gas industry. I’m going to show you how to bend tubing
and some important best practices to follow using a high pressure control valve package
as an example of some of the bends you’ll need to know how to make.
We’ll start by looking at a fitting which
includes four parts: the body, nut, front ferrule and back ferrule. Generally, you don't
want to take these apart ahead of time to avoid the possibility of getting any dirt
or debris inside. It’s good to know what the parts are, so when you’re putting it
together, you know how to layer the components. For all fittings on control valves and equipment,
we suggest using a thread sealant such as Loctite rather than Teflon tape to avoid the
potential of any tape getting inside the equipment. We recommend planning out a path ahead of
time so you can avoid tubing that crosses paths if possible. Taking some time up front
to figure out your paths can save you material and make your bends easier. On our packages,
we like to keep all the tubing as close to the valve body as possible to keep it out
of the way. If you’re installing a straight connector,
you can fully tighten it when you install it since there’s only one way the tube can
go in. However, to give yourself a bit more flexibility, don’t fully tighten any 90°
or elbow fittings until the tubing has been installed.
For this package, we’re going to start by connecting the upstream side of the valve
to the sense line. Apply sealant to the connection. Since it’s a 90° elbow fitting, we won’t
tighten it all the way yet.
One of the first things you can do on your tubing is make an end reference mark. This
mark will make sure you always know which side of the tube is your reference side, which
will go to the left of your bender. This first measurement will be taken from
the where the tubing touches the bottom of the nut to the center of where the bend will
be. I’m going to use a piece of scrap tubing to get an estimate of where this bend needs
to be.
Then measure and mark where you’ll make the 90° bend. The centerline radius (CLR)
is determined by the die size of the tubing benders.
It can be helpful to mark the whole circumference
of the tube so that no matter how it’s inserted into the bender, you can still see the line.
You can easily put this tool in a vise as we’re doing to help keep it steady and leave
your hands free to control the tubing. Lift the short arm of the bender and insert
the tube into the jaw of the bender. Align both zero markers on the tool, then adjust
the tube until your mark is aligned with the “L” position. For 90° bends, you always
align your mark with the “L”. Our reference side is on the left, so that’s why we use
the “L”. If the reference side is on the right, you would use the “R”.
Tighten the tube latch and make your bend. The zero on the arm will be your indicator
for the degree of bend you’re making. Pull the arm down until you reach the 90° mark.
You may need to bend slightly more than your
target angle to compensate for angular springback, which is how the tube will spring back a few
degrees when released. Don’t over bend it too far – you can always go back and add
more, but you can’t reduce an angle after it’s made.
Now we’ll be cutting our bent tube to length.
Insert the tubing in one fitting and make a mark where it aligns with the shoulder of
the fitting body. A tubing cutter works by rotating around the
tubing and gradually tightening the cutting wheel until it cuts through the tubing.
Position the mark in the cutter. Turn the handle until the wheel touches the tubing.
Then turn the handle an extra 1/16-turn. The marks on the handle indicate an 1/8-turn,
so use that as a reference. Rotate the cutter around the tube. After every
second rotation, turn the handle about a 1/16th of a turn until the tube is cut through.
After cutting the tubing, use a deburring
tool to remove any sharp edges or burrs from the tubing. This is an important step to ensure
that the tubing fits securely into the fittings without causing any damage.
To keep track of the amount of rotation, you can mark the tubing and nut in its starting
position. Hand-tighten the nut and then turn another 1 or 1-¼ turns with a wrench. Overtightening
can put too much pressure on the fitting. Do this for both fittings.
For our second connection, we’ll be using
a straight connector and one elbow. First, apply sealant to the connection. Fully tighten
the straight connection then hand start the elbow connector leaving a half turn to make
the installation easier later. For this piece of tubing, we’ll need two
90° bends. Measure to get a rough estimate of the length
of tubing you’ll need. Cutting a long piece of straight tubing is difficult to hold on
to while cutting, so you can lightly put it in a vise if you need. We’ll do a final
length cut later.
A quick trick you can use to get measurements for a bend like this is to use your tubing
set in the connector and some scrap tubing in the other connector. Line them up by eye
and use a straight edge or a level to get a more accurate measurement. Make your mark
on the center line. Using the same techniques as the other bend,
insert the tubing, align the zeros and put your mark at the “L”. Clamp down with
the latch and bend to the 90° mark.
For our second 90° bend, accuracy is more important now because we must reach our fitting
perfectly. Return the bent tube to the fitting, and slightly
move the scrap piece of tubing so it can rest in its final position. Mark the center line
on your tubing for your second 90° bend. Before clamping the latch down all the way,
make sure that your tubing bender is square with the bend you previously made. Check
the level of the tool, then check the level of the previous bend.
Secure the latch, bend the arm down to bring the zero to the 90° indicator, maybe a little
more, then release. With the tubing back in the fitting, mark
the final length based on the start of the shoulder of the fitting body. Make your cut,
again tightening after every second rotation. Deburr the end and you’re ready to install.
Hand-tighten the fittings, mark a reference point and turn 1 to 1-¼ turns.
On this example, we’ll be making a 90°
and an offset bend.
First, we’ll measure for the first 90° bend. Use a piece of scrap tubing in one fitting
and your actual tubing in the other. Use a level to mark where your centerline will be.
The length of tube before our mark is less
than the allowable amount for this tubing bender. Since we know we will need the shortest
amount of tubing possible before the bend, I’ll simply adjust it so the reference end
of the tubing is aligned with the latch.
A best practice when you’re making two bends on a single tube is to make a reference mark
on the top of the tubing, so you get the correct orientation of the bends.
Set in a scrap piece of tubing and measure the distance from the center line of the scrap
piece to the center line of the fitting. In this case, 3”.
For this piece, the offset just needs to clear the bonnet or any obstructions. Make your
mark and bend the tube, but for this bend, we’re not bending it to certain angle, we’re
bending it to achieve that 3” offset height.
For this bend use the mark you made earlier to help you align the tubing correctly for
your next bend. You’ll need more precision on this second bend, so use a level to get
your angle correct. Tighten the latch and make your bend.
This might be a little bit of a trial-and-error process, just don’t bend it too much. Bend
it close, get a measurement and adjust from there.
The reason we’re doing it this way instead of mathematically is because it’s just not
necessary for the type of connections we need to make here.
With our offset bend ready, mark the final length of tubing near the shoulder of the
fitting. Make your cut and deburr the end. Once the piece is in place, make reference
marks on the fittings and tubing to fully tighten the connectors.
For this connection, we’re going to use two straight fittings. The tube will have
two 90°s. We’ll start by fulling tightening the fittings using sealant.
Take a rough measurement of the amount of tubing you’ll need. Each side will need
to come out of the fitting and make a 90° bend.
Set the piece of tubing in the fitting and a scrap piece in the other. Use another piece
of tubing to mark the location of the first bend. Fortunately for this one, we can simply
eyeball the placement. Make your bend as we have before — insert
the tubing with the latch part way down, line up the zeros, align your mark to the L, tighten
the latch, and make your bend. With the piece back in the fitting on the
body, make your second mark on the tube according to how it lines up with your scrap piece.
This bend will need to be level with the previous one. Check the level of the tool, then level
the previous bend before making your second 90°.
Mark the tubing where it meets the shoulder of the fitting to make your final cut.
After deburring, insert the tube, hand-tighten the nut and then turn another 1 or 1-¼ turns
with a wrench.
Tubing bending and fittings are critical components of pneumatic devices in the oil and gas industry.
By following the best practices, tips, and tricks outlined in this video, you can ensure
that your tube bending and fitting installation is accurate, consistent, and safe.