Troubleshooting Major Causes of Rotary Joint and Rotary Union Problems

Globe Star Engineers (India) Pvt. Ltd.

PRESENTS

“Troubleshooting Major Causes of Rotary Joint and Rotary Union Problems”

·        As mechanical devices with wear components, rotary joints are suspect to premature wear when not correctly installed. Below are the leading major happens of premature wear and how to limit the potential for early replacement of components due to improper installation.

·        Improper Piping

Improper piping that leads to piping strains. Piping strains lead to excessive force exertion on the body of the rotary joint or excessive guide wear with self-supported rotary joints. For rod-supported rotary joints, the support rods deflect under the excessive piping strain and that causes poor seal alignment.

Prevent piping strains by using proper flexible metal hoses, piping support, expansion joints or loops, and accurate rotary joint or rotary union installation.

·        Rotary Joint or Union Misalignment

Rotary joint or rotary union misalignment occurs when the centerline of the rotary joint components are not accurately aligned with the centerline of the journal.  Misalignment can cause interference with the rotary joint’s internal parts and significantly increases the wear rate of the sealing components. Symptoms of rotary joint and rotary union misalignment include:

·        Broken spring

·        Excessive key and key-way wear

·        Broken horizontal siphon pipes

·        Broken journal flange bolts

·        Broken nipple flange studs

·        Flexible metal hose failures

·        Broken carbon guides

Prevent misalignment by accurately installing the rotary joint and supporting equipment.  Evenly torque journal flange and nipple flange fasteners.  Bent support rods or poorly aligned mounting brackets are common causes for misalignment as well.

·        Lack of/Improper Torque Restraint

Lack of a torque restraint or an improper torque restraint increases the radial forces that are applied to self-supporting rotary joints. Using flexible hoses as a torque restraint causes high radial loads to be applied to the rotary joint.  An overly restrictive torque restraint can cause excessively high forces as well.  A properly designed torque restraint allows the rotary joint or rotary union to move axially and radially while preventing rotation.

·        For more information :

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FACTORS AFFECTING THE SELECTION OF MECHANICAL SEALS

Presents

“FACTORS AFFECTING THE SELECTION OF MECHANICAL SEALS” 

1. Media Handled :

Corrosiveness of media decides the material of construction.
• Density of viscosity shows the lubricating properties of the media. This decides the seal arrangement.
                   

• Abrasives in the media decides the type of flushing plan required Corrosiveness of media decides the material of construction.
• Density of viscosity shows the lubricating properties of the media. This
decides the seal arrangement.
• Abrasives in the media decides the type of flushing plan required.

2. Stuffing box pressure :

• When stuffing box pressure < 10 kg. / cm2, unbalanced seals are used.
• When stuffing box pressure . 10 Kg. / cm2 , balanced seals are used.

3. Shaft Speed :

• With increase in speed the chance of seal running dry increases. So proper
flushing plan has to be decided which can give positive flush between the
faces.

4. PV Factor :

• PV factor is defined as the product of the pressure drop across the seal and
the average rubbing velocity. As a general guide, Seal capabilities can be
classified as, Low , if the PV value is 0.7 MPa m/s ( about 20,000 psi ft/min)
Medium, if the PV value is between 0.7 and 10 MPa m/s ( about 285,000 psi
ft/min) High , if the PV value ranges from 10 to 70 MPa m/s (about 2,000,000 psi
ft/min). Balanced seals reduce the pressure acting on the seal faces, therefore they have higher PV values than unbalanced seals.

5. Temperature :

• This decides the material of construction so that the seal does not fail at operating temperature.
• This will decides the seal flushing plan.

7 CONSIDERATIONS FOR MECHANICAL SEAL SELECTION

Globe Star engineers (India) PVT. ltd.

presents

7 CONSIDERATIONS FOR MECHANICAL

SEAL SELECTION

                                                 

Mechanical seals can operate for many years without issue, as long as they've been properly selected for their application. One must identify the application data (or operating conditions) to properly select the type of seal and materials of construction to ensure maximum performance from the seal over its lifetime. Below we define the operating conditions and discuss what material characteristics to consider for preventing improper material selection.

**Please note: There are many things to evaluate when selecting a seal, so be sure to speak with an experienced engineer before your final selection is made. 

LIQUID

Identifying the exact liquid being handled is the first step in the seal selection process. Seal material must be able to withstand the fluid being processed. All seal materials must be chemically compatible with the fluid, or there is an increased risk of seal failure. 

PRESSURE

Pressure in the seal chamber and seal size determines the type of seal required, balanced or unbalanced.

TEMPERATURE

Seal materials must be selected to appropriately handle the liquid’s temperature. Temperature is important because different seal materials are rated for certain temperatures and you should not exceed the temperature limit of these materials. 

LIQUID CHARACTERISTICS

Knowing the viscosity of the liquid is important to ensure appropriate seal life. Abrasive liquids can create excessive wear and will ultimately shorten the seal's life. Double seals or use of an external flush plan give operator's the option to use mechanical seals on these difficult fluids.

RELIABILITY & EMISSION CONCERNS

every company has their own standards and operating procedures when it comes to reliability and emission concerns for an application. The seal type and arrangement selected must meet the desired reliability and emission standards for the pump application. Since environmental safety has become a hot topic among manufacturing companies, double seals are peaking as the solution of choice.

After understanding the seal's exact operating conditions, you can select the seal's overall construction material and its face and component materials. When selecting the seal's material of construction, be sure to consider the following characteristics of the material:

• Temperature constraints
• Chemical resistance properties
• Flexibility 
• Wear resistance
• Thermal expansion and conductivity properties

And, when selecting the face and other component materials for the seal, consider these material characteristics:

• Wear resistance
• Low leakage & friction properties
• Good thermal properties
• Corrosion resistant

Industrial Water Pump Seal

Globe Star Engineers(India) Pvt. Ltd.

Manufacturer of Several Types of Mechanical seal, water pump seal, Rotary joint and Chemical process pump.

Industrial Water Pump Seal

Water Pump Seal

Water Pump Seal - Globe Seal is the largest manufacturer of water pump seal in India. We offer highly engineered Industrial water pump seal.

Industrial Water Pump Seals Suppler, Metal Water Pump Seal

Industrial Water Pump Seals Suppler - get metal water pump seal from globeseal.com! We are top best water pump seals Manufacture Company in India.

We have developed OP, G301, G155, G2100, G1, SB70 series of the seals. The industrial water pump seals are made of best quality raw material with technologically advanced instruments and machines. The seal can be varied as per requirement. Industrial Water pump seal is highly reliable and has long functional life.

·          

           

•        Easy to install and easy to operate
•          Perfectly finished
•          Dimensionally accurate
•          Sturdy construction 

   

    Types of Water pump seal. 

      1. Series G301

  

Application : Water, Sewage Oil Pump, Generators, Muddy Water

Features : Internal Mounting, Single acting. Independent of Direction of Rotation

Operating Conditions : -20°c .....to 100°c

Pressure : Upto 10 Bar (kg/cm 2)

Available Size : 10 mm.........100 mm

Shaft Speed : 5 m/sec.

    

    

     2.Series G155

   

     

Application : Water, Light Chemicals Viscous Fluids

Features : Single Acting, Dependent of Direction of Rotation

Operating Conditions : Temperature -20°c ...to 150°c

Pressure : Upto 10 Bar (kg/cm 2)

Available Size : 10 mm.........100 mm

Shaft Speed : 7 m/sec.

    3.Series G2100

    

Application : Water, Steam, Light Chemicals   Solvents

Features : Single Acting. Dependent   on Direction of Rotation

Operating Conditions : Temperature -20°c ...to 150°c

Pressure : Upto 10 Bar (kg/cm 2)

Available Size : 10 mm.........100 mm

Shaft Speed : 10 m/sec.

4.Series OP

Application : Water, Sewage Oil Pump, Generators, Muddy Water

Features : Internal Mounting, Single acting. Independent of Direction of Rotation

Operating Conditions : -20°c .....to 100°c

Pressure : Upto 10 Bar (kg/cm 2)

Available Size : 10 mm.........100 mm

Shaft Speed : 5 m/sec.

5.Series G1

Application : Water, Sewage Service, Light Chemicals, Muddy Water.

Features : Internal Mounting, Single Acting, Independent of Direction of Rotation.

Operating Conditions : Temperature -20°c ...to 150°c

Pressure : Upto 10 Bar (kg/cm 2)

Available Size : 10 mm.........100 mm

Shaft Speed : 10 m/sec.

Rotary union

Rotary union

This image shows the components needed to make a rotary union; a shaft, housing, bearings, seals and retaining clip. The independent shaft and housing allow for continuous rotation of either component. This is an example of a two passage rotary union with independent channels that allow both liquids and gases to transfer simultaneously. ^[1]

A rotary union is a union that allows for rotation of the united parts. It is thus a device that provides a seal between a stationary supply passage (such as pipe or tubing) and a rotating part (such as a drum, cylinder, or spindle) to permit the flow of a fluid into and/or out of the rotating part. Fluids typically used with rotary joints and rotating unions include various heat transfer media and fluid power media such as steam, water, thermal oil, hydraulic fluid, and coolants. A rotary union is sometimes referred to as a rotating union, rotary valve, roto rseal, rotary couplings, rotary joint, rotating joints, hydraulic coupling, pneumatic rotary union, through bore rotary union, air rotary union, electrical rotary union, vacuum rotary union

Rotary Joint Function, Types and Uses.

 

Function

A rotary union will lock onto an input valve while rotating to meet an outlet. During this time the liquid and/or gas will flow into the rotary union from its source and will be held within the device during its movement. This liquid and/or gas will leave the union when the valve openings meet during rotation and more liquid and/or gas will flow into the union again for the next rotation. Often functioning under high pressure and constant movement a rotary union is designed to rotate around an axis. A rotary union’s design can be altered to change this or to increase the psi or rpm it needs to withstand as well as the number of valves required.

Types of Rotary Unions

Many rotary unions incorporate multiple ports, some of which are designed to handle different types of material simultaneously. A rotary union with a straight port transfers the substance directly through the rotary union. Other designs include an elbow port, which causes the material to flow out at an angle, and multiple ports. A multiple port rotary union looks like a perforated cylinder. At the end of the cylinder is a threaded screw with seals that locks on to the output. The material being transferred flows into the cylinder and out of the input holes. In the case of a rotary union with multiple inputs, chambers separated by seals keep the materials from inadvertently mixing. This type of rotary union is often used in the manufacture of plastics and other petroleum products, for which multiple inputs may need to be streamlined, but kept separate.

Uses

Many assembly lines incorporate multiple rotary unions, because they are highly versatile and take up less space than other devices designed for a similar purpose. Rotary unions also appear in automobiles and other machines that require constant supplies of lubrication, air, or other liquids in order for moving parts to run smoothly. Brakes, for example, use rotary unions to maintain a constant supply of pressurized brake fluid. Rotary unions are also heavily used in crude oil processing, the chemical industry, commercial food production, and pharmaceutical applications.

Why Liquid Pump Seals Fail

Why Liquid Pump Seals Fail

When operating rotating equipment, some end users do not pay enough attention to transient conditions. Startup, slow-roll and standby pump conditions must be evaluated to ensure proper sealing fluid is being supplied to the seals at all times.

Startup: The pump is charged, but at or near suction pressure. Liquid ethane at the seal faces is slowly leaking and vaporizing. When the pump starts, how long does it take to build the right pressure in the stuffing box and get the pressure above vapor pressure? Additionally, the heat generation between the faces, although not significant, could be enough to increase vapor pressure and vaporize the fluid across the faces. Damage to sealing faces could be a telling sign that this is occurring.

Slow-roll: The same situation as startup but compounded. Without the right speed, the discharge pressure is not generated. The pressure in the stuffing box is not rising quickly enough to ensure the ethane will reach a high enough pressure to overcome the vapor pressure. Also, the heat generation between the contacting faces is increasing, and damage is probably taking place.

Standby: All conditions mentioned above are the same, but the seals are sitting idle for many months without a flush to the seals. During the standby time, evidence has shown that debris has collected at or around the seal faces, which, in turn, adds more complication to the sealing environment.

Inefficient operation: Operating the pump too far outside of the best efficiency range and with the wrong operating parameters results in increased demand for drive power and reduced discharge pressure. Both of these negatively impact the vapor margin in the seal area, which can result in dry running.