Key Inputs Required

1. Working Pressure 2. Test Pressure 3. Working Medium 4. Working speed range 5. Type of cylinder

I. Single Acting II. Double Acting III. Telescopic Cylinder IV. Through Rod

6. Type of Mounting I. Lug Mounting II. Flange Mounting III. Clevis Mounting IV. Trunnion Mounting

7. Working Temperature 8. Application

I. Material Handling II. Steel plant III. Dam Gate Opening IV. Construction Equipment

Materials for Different parts Outer Tube

1. Hot Finished Seamless Tube (HFS) 2. Cold Drawn Seamless tube (CDS) 3. Drawn Over Mandrel (DOM) 4. St 35, St 45 DIN: 2391 5. ASTM A513 Grade 1026 6. DIN 2393 ST52-3 BK

Piston Rod

1. 45C8 IS:5517 with or with out Q&T based on the application 2. En 19 with Q&T 3. SAE 4135 4. SAE 4140 5. Stainless Steel AISI 316 for low stress 6. Stainless steel AISI 431 for High stress

Piston

1. 45C8 IS: 5517 with Q&T. 2. SG500/7 IS: 1865 – If length of the piston is small and bearing support is required.

HEC

1. 45C8 IS:5517 2. SG500/7 IS:1865 3. Fe 410 WB IS: 2062

Depending upon the application or customer requirement we can other material like Phosphorus Bronze, Aluminium etc. Rod Eye.

1. 45C8 IS:5517 (Machined) 2. Class 2 IS:2004 (forging) 3. Class 4 IS:2004 (forging)

Sealing System for Cylinders

Seal Material code and selection characteristics

Seal Material Code Temperature Range Important Characteristics Min. deg C Max. Deg C Advantage Limitations

Butyl Rubber B 40 150 Good Ability in synthesis Relatively low shear strength

Neoprene Rubber C 50 180 Good weather resistance in exposed application

High Friction unless fabric reinforced

Ethylene Propylene rubber E 50 180 Good weather Slightly permeable to

high pressure gases. Fluorocarbon rubber (Viton) F -20 200 High temperature

resistance Slow memory, high mould shrinkage

Leather (chrome tanned polyurethane impregnated)

L 50 80

Low friction abrasion resistant (slight polishing action in bores high and low pressures)

Simple seal sections only

Nitrite rubber (Buna –N)

N 50 150 Good general purpose elastomer Poor weather resistance

PTFE (Polytetra Fluroethylene)

P 250 400

Wide material and fluid compatibility. Low friction. Available in tape cord and in moulded forms.

Slow memory

Polyurethane impregnated potomeric reinforced substrate

R 50 150 High abrasion resistance. Low friction high pressure

Poor resistance to synthesis and water when warm

Polyurethane V 20 100 Resistance to abrasion and extrusion

Poor resistance to synthesis and water when warm

Seal Material Selection guide

Fluid Type Preferred seal material code Do not use Static Dynamic

Mineral (Petroleum oil) F, N, C V, L, P, R E Phosphate Ester B E, P N, R, V, C Water glycol N, V P, N, V L Water C N, E, P R, V Nitrogen N, B, C N, B, P, V, F E Some of the suppliers of seals are

1. Hallite 2. NOK 3. Shamban 4. Parker 5. Multiseals

Choose the appropriate seals from the above supplier catalogue to get the gland dimensions, material, and properties.

NOTE: If the working temperature is more than 220 Bar, rod seal should contain primary seal and then secondary seals.

Type of Construction 1. Bolted Construction 2. Welded Construction 3. Threaded Construction 4. Tie Rod Construction

Bolted Construction:

- This construction is preferred where the bore of the cylinder is big enough to accommodate the bolts or screws used to bolting of piston and piston rod.

Welded Construction:

- This construction is used where the cylinder outer tube thickness is small. - In this the outer tube is welded to end covers.

Threaded Construction:

- This construction is preferred where the tube thickness is sufficient enough to accommodate threads and working pressure is low.

- It is also used where serviceability is important. Tie Rod Construction:

- This construction is preferred for very small cylinders and where working pressure is very low.

Through Rod Construction

- This construction is normally used for small cylinders. - In this the piston rod runs through out the length and the piston may be welded or

press fit onto the piston rod.

Hydraulic Oil Oil used for Hydraulic application is mainly mineral oil. The primary purpose of any hydraulic fluid is

1. Transmission of Power: Hydraulic oil has to transmit power mechanically through out the Hydraulic system.

2. Lubrication : Hydraulic fluids must provide the lubricating characteristics and qualities necessary to protect all hydraulic system components against friction and wear

3. Sealing: Many hydraulic system components, such as control valves, operate with tight clearances where seals are not provided. In these applications hydraulic fluids must provide the seal between the low-pressure and high-pressure side of valve ports

4. Cooling: The circulating hydraulic fluid must be capable of removing heat generated throughout the system.

Physical Properties of oil: Viscosity: As with lubricating oils, viscosity is the most important characteristic of a hydraulic fluid and has a significant impact on the operation of a hydraulic system. If the viscosity is too high then friction, pressure drop, power consumption, and heat generation increase. Furthermore, sluggish operation of valves and servos may result. If the viscosity is too low, increased internal leakage may result under higher operating temperatures. The oil film may be insufficient to prevent excessive wear or possible seizure of moving parts, pump efficiency may decrease, and sluggish operation may be experienced. Compressibility: Compressibility is a measure of the amount of volume reduction due to pressure. Compressibility is sometimes expressed by the “bulk modulus,” which is the reciprocal of compressibility. Petroleum fluids are relatively incompressible, but volume reductions can be approximately 0.5 percent for pressures ranging from 6900 kPa (1000 lb/sq in) up to 27,600 kPa (4000 lb/sq in). Compressibility increases with pressure and temperature and has significant effects on high-pressure fluid systems. Problems directly caused by compressibility include the following: servos fail to maintain static rigidity and experience adverse effects in system amplification or gain; loss in efficiency, which is counted as power loss because the volume reduction due to compressibility cannot be recovered; and cavitations, which may cause metal fracture, corrosive fatigue, and stress corrosion. Properties of Mineral oil (Hydraulic grade) Specific gravity at 100 deg F, Atmospheric Pressure : 0.86kg/ (8.6 lb/imp. gal) Specific heat at 100 def F : 1.97kj/kg K. Thermal Conductivity : 0.001 26 W/cm K (0.000 30 cal/cms C) Closed flash point : 205 C (400 F) Pour point : -29 deg (-20defg F) Viscosity at 37.8 deg C and atmospheric Pressure : 30~60cst Viscosity at 37.8 deg C and 5000lbf/in2 : 85~140cst. Compressibility, approximate reduction in volume at 69bar (1000 lbf/in2) : 0.038

Selection of the oil is based on the following parameters: 1. It should have good self lubricating properties. 2. It should be anti-corrosion properties. 3. It should be incompressible. 4. It should be Non-Oxidizing. 5. It should have antirust properties. 6. It should not be entrainment. (should not form foam with air). 7. It should have high viscosity index.

Requirements of Petroleum based fluids

1. Min Viscosity Index as per ASTM D 567- 90 2. Specific gravity at 60 deg : 0.84~0.90 3. Minimum Aniline point as per ASTM D-611: 100 4. Rust as per ASTM D-665 5. Hydrolytic Stability as per ASTM D-2619

I. Max Copper wt. loss(mg/cm): 0.2~0.5 II. Max. Water acidity(mg KOH): 4~6

Some of Hydraulic oils used are

1. ISO VG. 10 2. ISO VG. 15 3. ISO VG. 22 4. ISO VG. 32 5. ISO VG. 46 6. ISO VG. 68 7. ISO VG. 100 Commonly used hydraulic oil is ISO VG. 46 or ISO VG. 68.

Customer Requirements & Data Capturing sheet

Customer

No. of Stages

Bore (mm/inch)

Rod (mm/inch)

Stroke (mm/inch)

Working Medium

Ret

ract

ion

Working/System Pressure (kg/cm2)

Ret

ract

ion

Test Pressure (Kg/cm2)

Working Temperature

Working Speed

Type

Mounting

Installation

Horizontal Vertical Inclined Down Inclined up

Where DA = Double Acting TM= Trunnion Mounting SE = Single Acting Cap end CM= Cap end Mounting SH = Single Acting Head End TR = Through Rod CF = Cap end Flange HF = Head End Flange LM= Lug Mounting

DA SE SH TR

CF HF LM TM CM

Mineral oil Any other specific

Any other specific Mineral oil

Telescopic

Validation & Testing Cylinders are usually tested for endurance and leakages (internally and externally). The tests include

1. Cycling test 2. Proof Pressure Test

Cycling Test: Cycling test is done to check for performance. Usually in this test, the cylinder is

mounted on the test rig and hydraulic oil is made to flow through the ports (if it is a double acting) so that the cylinder is extended and retracted back alternatively. This is done to check the performance of the cylinder. Single acting cylinder usually requires a slave cylinder or natural force to bring it back it its normal state (closed condition).

Proof pressure test. In this the cylinder is extended for the full stroke and pressure is applied to check for

any failure. In this the pressure applied is usually 1.5~2 times the normal working pressure and for a period of 3 sec. During this the seals inside are pressurized and de-pressurized accordingly. By this we can know the performance of the seals used and also the soundness of the material used. After testing check whether the tube has bulged and during testing check whether there is any leakage externally like leakage from welding, threaded parts.

Internal Leakage Test. In this the piston is positioned at its mid stroke. Rod and end cover is secured to the

test rig. After securing the cylinder, cap end port is pressurized to the rated pressure and held at that pressure for some time. If there is any internal leakage the pressure on the cap end side reduces indicating that there is an internal leakage.

For know further about testing refer IS: 10585.