Flange Facing (the easy way)
Flanged connections are found all throughout industrial plants. It is critical to the efficiency and safety of each plant that these flanged connections operate leak-free. Not only does the plant's process lose efficiency by wasting spilt materials in the event of a leak, but a leak can also pose a serious danger to plant personnel, especially if the fluids are under pressure, flammable or toxic. That is why it is important to resurface damaged or corroded flanges before joining them together and putting them into service. In this article we will introduce you to a new tool that is making flange facing of small flanges quicker and easier than ever before.
Typically when a flange has been taken out of service for a period of time or a new flange is waiting to be put into service, it is stored with a flange protector to guard against corrosion and damage. However, when the flanges are being moved around and fitted for welding it is not uncommon for them to accidently get knicked or damaged. These dings can easily lead to a leak and a QC/QA Manager will spot them right away. In the past, this meant that you would either remove the flange (which may involve cutting away a weld and having to re-weld it on later) and send it off to a machine shop for resurfacing or you would machine the flange in-place with a portable flange facing machine (which requires technical training and expertise to operate correctly).
Once you have discovered your flange is damaged you'll want to evaluate the extent of the damage. Is this a deep gash in the flange surface? Are there one or more small knicks? If the dings are deep enough, you'll likely need to add weld build-up and machine the flange face back to flat with a gramophone finish. This is done to avoid diminishing the raised face flange surface too much by removing too much material.
If the knicks are not deep enough that weld build-up is required, you won't need to remove much material to get a nice mating surface. If this is the case and the ID of your flange is between 1" - 10.5" then you can use the FlangeHog110 tool from Esco Tool to make quick work of this resurfacing project. Here's how to use the tool:
Step 1: Measure Your Flange ID
You can use the edge of the clamp rib chart that is provided with the tool to measure the ID of the flange.
Step 2: Attach the Correct Clamp Ribs
The FlangeHog110 uses the same tried-and-true internal clamping method as the Millhog series of pipe and tube beveling machines from Esco Tool. These ribs are self centering and lock rigidly to the ID of the pipe as you tighten the draw rod. Refer to the clamp rib chart to select the proper clamping ribs and wedge size for your application. You will need to change the clamp rib springs out if the flange is over 5.5" ID and you need to utilize the large wedge.
Step 3: Mount the Tool
Now you'll want to mount the tool to the ID of the flange. You ideally will have about 2" of straight run inside the flange to mount to, however, if your application allows for less internal straight run to clamp onto we can supply short clamp ribs to minimize this requirement.
If using the small or medium wedges, simply stick the mandrel into the ID of the flange and begin cranking on the ratchet that tightens the draw rod and expands the clamp ribs into the ID of the pipe. You will feel the tool get snug and this means the tool is centered and rigidly clamped into the pipe ID.
If using the large wedge (about 5.5" ID - 10.5" ID flanges), you'll want to loosen the leveling legs on the large wedge and spread them out. These legs will rest on the flange face surface to get you close to a level setup. With the legs extended, crank the ratchet on the draw rod to snug the tool to the ID. Once snug, loosen each leg and fold it back onto the large wedge. Now you'll want to attach the magnetic dial indicator that is provided with the tool to the tool post and touch it to the flange face surface. Zero the dial indicator and rotate the tool around the circumference of the flange face. Notice the action of the dial indicator hand and make note of where the low and high spots are. If the hand moves more than about 5 thousandths in either direction, you'll want to take a small hammer and punch and tap the clamp rib while watching the dial indicator. Split the difference, spin the tool around to your starting point re-zero the indicator and measure it again. Repeat until you are within a few thousandths (or however accurate you want it to be) and this will ensure that you are making a level cut into the flange face surface.
Step 4: Select Depth of Cut
Now with the tool centered, leveled and snug to the pipe ID it's time to set your depth of cut. The FlangeHog 110 comes with a fine feed tool holder with marked notches to indicate every .004" depth. Typically, we recommend making .004" cuts per pass because the tool will remain light and easy to rotate this way. You can make deeper cuts if you wish but it will be more and more difficult to rotate the tool the deeper the cut is. It can actually be easier to make twice the number of passes by removing less material per pass.
Step 5: Rotate the Arm
Now with the tool centered, leveled, snug to the pipe ID and the depth of cut selected it's time to rotate the arm of the tool and make our cut. The tool is designed with an internal worm gear that rotates your feed screw as you rotate the tool so that it feeds the tool insert outwards as you rotate the tool clockwise. You can change the feed screw from Stock to Smooth finish to achieve your desired surface finish.
Rotate the tool until you have covered the radius of flange surface you want to machine.
Once you have completed the flange facing, you can now either remove the tool or manually feed the tool post back to the ID of the flange and advance your tool insert another .004" to make another pass.
Gulf States Industrial Inc.