What is snubbing on a road?
This braking technique is called "snubbing." When operating any commercial vehicle, do not ride the clutch, race the engine, change gears or coast while driving down the grade. At the bottom of the grade, be sure to cancel the 4-way flashers.
What is a snubbing unit?
In essence, a snubbing unit is a hydraulic rig that can do everything a rig can do, plus it can perform under pressure in an under balanced live well state. This is especially critical to the operators in the Haynesville Shale, which is known for HPHT wells. With the use of the snubbing units' hydraulic rotary,...
What does snubbing a well mean?
The act of putting drillpipe into the wellbore when the blowout preventers (BOPs) are closed and pressure is contained in the well. Snubbing is necessary when a kick is taken, since well kill operations should always be conducted with the drillstring on bottom, and not somewhere up the wellbore.
What is snubbing on a downgrade?
Repeat this procedure as often as necessary until you have reached the end of the downgrade. This braking technique is called "snubbing." When operating any commercial vehicle, do not ride the clutch, race the engine, change gears or coast while driving down the grade. At the bottom of the grade, be sure to cancel the 4-way flashers.
What is a snub braking method?
0:002:33Mr. John Tutorial: Snub Braking - YouTubeYouTubeStart of suggested clipEnd of suggested clipAlright I'm gonna demonstrate snub breaking it's not breaking is when you do periodic breaking toMoreAlright I'm gonna demonstrate snub breaking it's not breaking is when you do periodic breaking to bring the speed. Down. I'm gonna do it at five miles an hour at a time forty-five down to 40.
How do you break a downhill semi truck?
2:386:49How to Brake Downhill Safely | Air Brakes Smart - YouTubeYouTubeStart of suggested clipEnd of suggested clipSingle-digit grade fifth gear in a tandem tandem if you're running heavier in a tandem tan or youMoreSingle-digit grade fifth gear in a tandem tandem if you're running heavier in a tandem tan or you got dual digits go down into fourth Jake brake on run the Jake between 15 and 1800.
What is controlled braking in trucking?
Controlled braking: With this method, you apply the brakes as hard as you can without locking the wheels. Keep steering wheel movements very small while doing this. If you need to make larger steering adjustments or if the wheels lock, release the brakes. Reapply the brakes as soon as you can.
Why should you be in the proper gear before starting downhill?
Why should you be in the proper gear before starting down a hill? So you only have to apply the brake just hard enough to feel a definite slowdown. So you don't have to shift gears going downhill. So you can go through the gears on the way down.
Can a Jake brake Fail?
The stopping power of Jake brakes is very strong. Without proper traction or weight on the tires, application of the brake could cause the truck to skid, resulting in loss of control or a jackknife accident.
Why do big trucks lose their brakes?
The Truck or trailer has a manufacturring defect; The truck or trailer has a design defect; The trailer or truck has been overloaded (loaded beyond its capacity, causing the brakes to fail; and. Improper maintenance including failing to check the brake pads.
What is a CDL retarder?
CDL retarders are found on some commercial vehicles and are designed to help slow a vehicle and reduce the need to use your brakes. When used properly, the retarders reduce your brake wear and provide you with another option for slowing down.
What are the types of retarders?
The four basic types of retarders are exhaust, engine, hydraulic, and electric.
At what PSI is the safety valve set to open?
Explanation The safety valve protects air tanks and the rest of an air brake system from accumulating too much air pressure. The safety valve is usually set to open at 150 psi.
Which gear is best for uphill?
If you're using a manual transmission, use second or third gear when you head up a steep incline – and don't change gears once you've committed to the climb. Failed Climb: Put the vehicle in reverse to allow for natural engine braking and keep tires turning.
What gear should you be in going uphill automatic?
Shift to Low Gear Why? This is because you need to have enough pulling or engine power to safely climb an inclined road. What you need to do is shift to a low gear, which is either the D1, D2, or D3 that's found on your car's gear lever. Of note, some automatic cars have it labeled as L, 2, and 3.
How often should you drain your air tanks CDL?
dailyRemember: Manual air tank drains must be drained daily in order to get rid of water and oil inside the air tanks. You may be asked about this on the written exam. Make sure you remember that the safety relief valve generally opens at 150 psi.
What is the proper method of braking on long downhill grades?
On long downhill grades, experts recommend using a low gear and light, steady pedal pressure instead of on-again, off-again braking.
Should you brake when going downhill?
Engine braking is a more effective way to reduce your speed while traveling downhill. MAT Foundry Group, a British manufacturer of automotive safety parts, says that when you take your foot off the accelerator, the airflow to the engine is restricted.
How do you use engine braking downhill?
1:466:59HOW TO use engine brakes on steep downhill with auto trans ... - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo when you're going downhill. My rule of thumb is just hit them pretty hard for about 3 seconds.MoreSo when you're going downhill. My rule of thumb is just hit them pretty hard for about 3 seconds. And then let them off let them cool down but the engine safely.
What should you do to brake while traveling downhill?
Explanation While driving downhill, you should hold down the brake pedal until your vehicle reaches a speed 5 mph below your safe speed, then release the brake pedal. Repeat this process.
How do truck brakes work?
Drivers also need to understand how truck brakes are activated when they press down on the treadle valve. What the treadle produces is just an air signal that travels the length of the rig. The bulk of the air is stored in tanks near each axle. The air signal from the treadle valve opens a relay valve near each axle to supply air rapidly, as signaled, to the brake chambers. The problem of downhill braking is getting all the relay valves to open.
What does snubbing a truck mean?
Snubbing means all the relay valves will be well beyond their crack pressures. All the drums will be working. And if the brake system is in sound condition, the truck will not experience significant brake fade.
How many brake drums are there in a tractor trailer?
With 10 brake drums, a modern tractor-trailer rig has enough total metal exposed to outside air to throw off the heat generated by braking. Heat is actually thrown away as fast as it is generated, and the brakes continue to operate efficiently. Problems occur if only six or eight of the 10 drums are working. This can happen if the crack pressures aren’t all the same and the driver brakes steadily at an apply pressure between those crack pressures. Both improper design and imperfect maintenance can easily skew the crack pressures, a problem referred to as a lack of brake system balance.
How much pressure to apply brakes?
After that, they repeat the cycle. If the driver has an air application gauge and knows how to read it, this means an applied pressure of 20 to 30 psi.
What happens when you have too few axles working?
The result of having too few axles working is excessive heat in the drums doing more than their share of the work. At high temperatures drums expand away from the linings, reducing application force. Also linings lose their grips on drums at elevated temperatures. This is called heat fade, and it can result in a runaway truck.
Do trucks have ABS?
Modern trucks may have ABS, but most of the brake system is mechanical technology. And ABS doesn’t do a thing to help keep brakes cool in a long, gradual descent.
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What is a snubbing rig?
Snubbing rigs are used for well completion and intervention operations where the pipe needs to be run into the live wells. Live wells are the wells under pressure. Similarly to coiled tubing, work string is pushed into the well to overcome well pressure forces.
What type of pipe is used for snubbing?
However, instead of continuous flexible pipe, snubbing rigs use conventional pipe which is screwed together with threaded connections.
What are the advantages of snubbing rigs?
Advantages of Snubbing Rigs. Can work on live wells – this eliminates the need to kill the well, makes operations cheaper and prevents damage to the formation caused by kill mud. Higher pump rates – bigger ID of the pipe allows higher pump rates than coiled tubing.
Why is snubbing pipe stiffer than coiled tubing?
This is possible because the pipe used for snubbing is much stiffer than coiled tubing. This also means that it takes much more force to buckle the pipe used for snubbing. This usually allows snubbing rigs to get deeper in the well than coiled tubing units.
How much weight can you lift on a snubbing rig?
Able to lift up to 50 lbs. First aid and H2S certificates. Driver’s license (Class 1 preferred)
What is the point where a pipe light becomes heavy?
The point where the pipe light becomes pipe heavy is called the balance point . When the pipe just starts to run into the well under pressure, pressure forces will try to push the pipe out of the well.
Does a snubbing rig rotate?
Ability to rotate the pipe – in situations where the pipe needs to be rotated, the snubbing rig has an advantage over coiled tubing or wireline. Higher set down force at the tool – more force is transferred to the bottom hole assembly in comparison to coiled tubing. This is possible because the pipe used for snubbing is much stiffer ...
What is snubbing in frac?
Snubbing is when you enter a pressurized well with pipe. Snubbing is commonly required to bring a well into production once it has been hydraulically fractured. This is because the plugs used for zonal isolation during the frac needs to be drilled out.
Why do we need to snubb a well?
This is because the plugs used for zonal isolation during the frac needs to be drilled out.
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What is pipe heavy?
Pipe heavy occurs when either enough pipe has been snubbed into the well bore and fluid weight inside of the pipe is greater than the snub forces acting against the pipe in the well bore. While snubbing into the hole, there is a transition point the tubular goes through from being pipe light, to pipe heavy.
How does a snubbing unit work?
Modern snubbing units are powered by sophisticated hydraulic systems. These hydraulic units typically supply all power required by the components of a snubbing operation. With a better understanding of hydraulics and modern advances, companies have been able to harness this hydraulic energy to develop precision controlled snubbing units. These units move tubulars into and out of a well bore by use of a "multi cylinder jack"; a snubbing jack comes in many sizes depending on the task at hand. They are usually denoted in size by the snubbing unit description (i.e. 460K, 340K, 200K, etc). The 460K snubbing unit has the ability to lift 460,000 LBS and a snubbing capacity of 230,000 LBS. Most snubbing units can typically snub half of their lift rating. Assume you had a well with 10,000 PSI at surface and wished to snub in a string of 2 3/8" tubing. The snubbing contractor can calculate the snub force, add in their respective friction calculations and project the snub force to overcome will be approximately 51,000 LBS. This would put a 120K snubbing unit to close to its maximum capacity of 60,000 LBS snub loading. The safest bet would be a 150K or 235K snubbing unit.
What is a snubbing basket?
The snubbing "basket" is the platform where the snubbing personnel work. The basket contains all of the necessary hydraulic controls to operate all the features of the snubbing unit, as well as a large bank of BOP's and hydraulic valve controls.
How high is a gin pole?
The gin pole is typically telescoped out in excess of 40ft above the snubbing unit. With the use of dual tubing winches, multiple joints of pipe can be handled simultaneously, speeding up the operation. The snubbing "basket" is the platform where the snubbing personnel work.
What are the components of a snubbing unit?
Components of a Snubbing Unit. One of the main components of a snubbing unit is the slip. Stationary and travelling slips are operated in sequence to grip the pipe as it is snubbed into the well. Typically, a minimum of four slip bowls are used in snubbing operations. Two slip bowls are designated for "pipe light" operations.
Why use a snubbing unit?
Another clear advantage to using a snubbing unit is its' small footprint, which is critical on the tight locations in the unconventional shale's. Moreover, the small size and ease of mobilizing is especially useful and cost effective with offshore wells.
When was the snubbing unit invented?
In the 1920's, the need for a rig to work with pressures at surface drove the invention of the snubbing unit. The first snubbing unit was primarily designed to work in well control situations to "snub" drill pipe and or casing into, or out of, a well bore when conventional well killing methods could not be used.
