John Crane GmbH
Gleitringdichtungssysteme
GB
Instruction Manual Mechanical Seal SUPPLIER DOCUMENT REVIEW PERMISSION TO PROCEED DOES NOT CONSTITUTE ACCEPTANCE OR APPROVAL OF DECISION DETAILS, CALCULATION. ANALYSIS TEST METHODS OR MATERIALS DEVELOPED OR SELECTED BY SUPPLIER AND DOES NOT RELIEVE SUPPLIER FROM FULL COMPLIANCE WITH CONTRACTUAL OBLIGATIONS. 1. 2. 3. 4.
WORK MAY PROCEED REVISE & RESUBMIT, WORK MAY PROCEED SUBJECT TO INCORPORATION OF CHANGES INDICATED. REVISE & RESUBMIT, WORK MAY NOT PROCEED. REVIEW NOT REQUIRED, WORK MAY PROCEED.
P.O. NO.
ORIG.
EQUIP. TAG.
DATE
ENPPI SUPP. DOC. NO.
Item no.
REV.
John Crane Engineered Sealing Systems
GB
Instruction Manual Mechanical Seal
Instruction Manual
Page: 2 of: 16 Edition 7.6
Contents 1
General..............................................................................................3 1.1Introduction.........................................................................................3 1.2Range of Application ..........................................................................3
2
Safety & Environment......................................................................3 2.1Symbols .............................................................................................3 2.2Safety Instructions..............................................................................3 2.3Environmental Aspects.......................................................................4 2.3.1 Company policy extract..........................................................4 2.3.2 Recycling ...............................................................................4
3 4
Transportation and Storage ............................................................5 Description of the Mechanical Seal ................................................5 4.1Construction .......................................................................................5 4.2Function .............................................................................................6 4.3Operating Conditions..........................................................................6
5
Installation and Removal .................................................................6 5.1Preparation for Fitting.........................................................................6
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Instruction Manual
Edition 7.6
1 1.1
General
This Instruction Manual is provided to familiarise the user with the seal arrangement and its use. The Instructions must be read and applied whenever work is done on the seal, and must be available to the operating and maintenance personnel. These instructions will help to avoid danger and increase reliability. John Crane reserve the right to change the seal and specifications described in this manual where it is necessary for technical development and without prior notice. The latest issue supersedes all previous versions.
1.2
Danger
Introduction
Range of Application
Mandatory instructions designed to prevent personal injury or extensive damage. ATTENTION Special instructions or
information to avoid damage to the seal or its surroundings.
Note:
Information for easy installation and efficient operation. Environmental Note
2.2
Safety Instructions
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Instruction Manual
Edition 7.6
ATTENTION Some mechanical seals are used in conjunction with an auxiliary support system; this is clarified by the flush plan description described on the seal arrangement drawing. It is important for the safe function of the seal that the support system is assembled and incorporated into the machine before operation. This Instruction Manual should be read in conjunction with the appropriate documentation for auxiliary systems and rotating equipment. Alarm systems are often included in the auxiliary support system and the operator must ensure appropriate action is taken promptly in the event of an alarm. Maintenance with steel tools must be avoided in the presence of substances classed as explosive group IIc according to EN50014.
John Crane adopts the ‘Design For the Environment’ (DFE) principle in making this product. Using this product will benefit the environment directly by:
Reducing waste of precious resources through decreasing the risk of leakage & minimising energy consumption Preventing pollution through controlling harmful emissions to the atmosphere Preserving valuable materials resources through the re-use of these high quality durable seals due to their ability to be refurbished.
2.3.2 Recycling
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Edition 7.6
Special materials Follow the local relevant guidelines for the environmentally friendly disposal of assembly lubricants, supplied fluids and scrapped components. Compounds containing PTFE, fluorocarbons and perfluoroelastomers should never be burned as the fumes and residues are highly toxic. Please refer to Safety Instructions- Section 2.2.
Packaging All packaging materials used are made from recyclable, environmentally friendly materials. When in doubt or for further information and advice on this subject, please consult John
Crane.
3
Transportation and Storage
For additional information on transportation and storage refer to John Crane document I-Storage. The sealing system does not require a ny preservatives; it is resistant against all normal environmental conditions. If any machine, with an installed seal, has been stored with preservatives before putting it back into operation then the seal must be removed, cleaned and dried. Particular attention must be applied to the cleanliness of the faces and condition of the elastomers.
ATTENTION
Ensure preservatives and cleaning agents do not affect the elastomers.
Once the seal is fitted on the ATTENTION machine and the position is set using setting devices do not re-engage them for transportation and storage.
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Instruction Manual
Edition 7.6
4.3
Fig. 2:
Typical Metal Bellows Mechanical Seal
Primary seal components a) primary ring b) mating ring
Secondary seal component c) static seal d) static seal
Spring component e) metal bellows
Drive and retaining components f) compression collar
Operating Conditions
Refer to data recorded on drawing and Seal Data Sheet (if applicable) in Section 9 and referenced on the front page. If no data is available refer to John Crane’s published Product Data Sheet specific to the seal type used (see www.johncrane.com), or consult John Crane direct. The seal cartridge has been selected to safely contain the maximum static seal chamber pressure. Any change from the original, specified pump operating conditions, including casing and/or piping hydrotest may compromise this safe containment. Refer to the Seal Data Sheet specific to the plant item or consult John Crane for the maximum sealingpressure rating of the seal cartridge.
Instruction Manual
Page: 7 of: 16 Edition 7.6
5.2
Installation Tolerances
The performance and reliability of the sealing system is influenced by the installation tolerances. Ensure that the tolerances do not exceed the required limits.
Carry out fitting according to the installation drawing (section 9 and front page) and with the following procedure:
5.2.1 Shape and Positional Tolerances Component
Type
Shaft to Housing
Squareness
Shaft to Housing
Concentricity
static
Shaft End Float Axial
Tolerance
1µm/mm chamber bore FIM* 0.13 mm
Where appropriate fully engage the specified eyebolt or eyebolts into the tapped hole and connect to safe lifting equipment.
± 0.25 mm
____________ _________________
dynamic
A tapped hole on the top of the gland plate is provided for those cartridges requiring additional mechanical lifting assistance. Refer to the Installation Drawing (see Section 9 and front page) for the recommended eyebolt type and size. On vertical shaft machines two linked collar eyebolts should be used. Eyebolts are not ordinarily a part of the scope of supply.
± 0.065 mm
Shaft or Sleeve
Ovality
0.05 mm
Housing to
Runout
0.05 mm
Eyebolts must meet the appropriate National Standards and their availability and use should be part of a local QA programme.
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Edition 7.6
ATTENTION
ATTENTION
ATTENTION
Silicone-elastomer O-rings are not resistant to silicone oil or grease. When the sleeve is fixed to the shaft by shrink disc, the area under the clamp must be kept free of lubricant (see Section 5.5). The seal faces should not be lubricated with oil or grease as this may prevent introduction of the sealed fluid in operation, leading to overheating and failures.
Ensure the seal arrangement is orientated correctly, according to the housing, pipework, and shaft connections (e.g. studs, keyways, pins and drive holes). On double-ended pumps
If not indicated refer to Section 5.3.1. Torque levels for gland plate studs or bolts must conform to those given in the relevant rotating machinery manual. For cartridge seal designs that do not have a metal-to-metal contact between the gland plate and the seal chamber face it is important they are aligned and the axial gap between them is equal around its circumference. This can be checked with a gap gauge.
ATTENTION For high temperature metal bellows seals e.g., 1604, 2609, 3609 etc the pump shaft may need dimpling to ensure adequate drive. Check on the drawing in Section 9. If required bolt the seal assembly to the pump back plate and finish assemble the pump so that the shaft is in its final position relative to the casing. In the case of hot pumps where thermal growth is known to be a problem,
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Instruction Manual
Edition 7.6
If possible check for freedom movement by hand turning the shaft.
of
Check on all pipework, hoses and fittings:
5.3.1 Tightening Torques Tightening Torques [Nm] (u 0.125 lubricated) Thread Legacy Socket Socket Socket Size
Remove and discard any plastic plugs used during transit.
Size
Setscrew
Setscrew
Setscrew
Code
(ASTM A453Gr 660 C) GMC 0649
(316) GMC 0550
(High Tensile Steel (14.9) GMC 0225
- lubricated
- lubricated
- lubricated
Legacy
Legacy
Legacy
Part Code
Part Code
Part Code
Ensure correct location, alignment and support Ensure all porting is correctly connected and the intended fluids flow at the correct flow rate. Refer to installation drawing (see Section 9) and relevant rotating machinery manual or P & ID. Ensure correct size pipework and specification. All unused connections must be safely plugged with the as-supplied metal pipe plugs. Check whether drain connection should be open or piped to a collection
Size/305/712 Size/305/001 Size/305/050 M4
77**
N/A
1.5
2.5
M5
78**
N/A
3
4.5
M6
79**
6
4
7.5
M8
80**
15
11
18
M10
81**
30
16
36
M12
82**
50
40
60.5
M14
83**
N/A
N/A
N/A
M16
84**
N/A
N/A
N/A
M20
86**
N/A
N/A
N/A
1/4 - 20
35**
6
7.9
9.8
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Edition 7.6
These torque values are important for the safe operation of the seal assembly and sleeve retention. Retention calculations assume a maximum shaft hardness of 32HRC (301HB, 318HV). If the shaft surface has a higher hardness specification contact John Crane for advice.
5.5
Installation and Removal of Shrink Discs (John Crane supply*)
Outer Locking Screw Inner Ring Sleeve
5.3.2 Lubricants The following lubricants are recommended by John Crane: Application
Lubricant
Note
All o-rings except for food, pharmaceutical and related applications
Du Pont Apply very Krytox® FG24 thinly by hand
All o-rings for food, pharmaceutical and related applications
Consult machine manufacturer
All fasteners except for food, pharmaceutical and related
Molybdenum Apply with or nickel based brush or by
Shaft
grease-free
Installation The shrink disc is supplied ready to be installed on the sleeve, and should not be dismantled prior to the initial installation.
Degrease sleeve bore and shaft! Slide seal
haft. Low
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Instruction Manual
Edition 7.6
Loosen all locking screws uniformly, in a clockwise sequence; initially about a quarter turn per revolution only. Do not remove screws from the threads.
If the outer and inner rings have not separated, remove some screws and insert them in the neighbouring extraction screw threads.
6
The shrink disc may have to be cleaned and re-greased before re-assembly (use a grease containing MoS2 on the shrink disc cones and locking screws).
Commissioning and Decommissioning
Note before start-up:
Regular venting may be ATTENTION needed during commissioning on Plan 23, particularly on vertical machinery.
If the seal cartridge requires auxiliary systems for its reliable operation refer to the separate Instruction Manuals for
If the seal is unidirectional, check that the seal’s rotation direction matches the machine’s rotation direction. With liquid lubricated seals avoid dry running under any circumstances, as it will damage the seal and may result in a hazard. (Not relevant to gas lubricated seals and dry containment seals).
Ensure that if a bearing is ATTENTION fitted as part of the seal assembly the Instructions on the Installation drawing (see Section 9 and front page) are applied. Bearings must not be run without lubricant.
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Edition 7.6
Before start-up, ensure that all personnel and assembly equipment have been moved to a safe distance, that guards are fitted and there is no contact with rotating parts.
To minimise any ignition hazard it is important to ensure seal flush rates, temperatures, and cooling water flow rates are to specification.
In case of pressurised or unpressurised dual seals note:
Auxiliary barrier systems are designed to service mechanical seals by cooling, lubricating and pressurising; they must be operated within their performance limits. If the barrier system is not supplied by John Crane check the system and specification supplied meet the seal’s requirements for reliable operation. Refer to the system
During the start-up of the machine in cold ambient conditions the barrier or buffer viscosity should not exceed 150 cSt. If this cannot be ensured the liquid is to be preheated. Interconnecting pipework between the system and the gland plate must be the correct specification and its length, bend radii, numbers of bends must be as recommended in the system Manual. They must all be continuously rising to aid venting. Effective seal cooling is achieved by maintaining adequate buffer or barrier liquid flow rate. This is strongly influenced by the system pipework resistance and any trapped gas in it. Recommendations must be applied.
Where a liquid based seal buffer auxiliary system is fitted to non-pressurised dual seals, ensure that the liquid level is correct
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Edition 7.6
The barrier pressure for liquid lubricated seals should be set at least 1 bar above the maximum seal chamber pressure. If a low-pressure switch or alarm is fitted to the system ensure it is set above the maximum seal chamber pressure and below the barrier pressure; there must be an adequate pressure difference between its set point and the barrier pressure to allow the switch to reset. For gas seals the minimum barrier pressure must be 2 bar for 2800E, 2800ER, 2874 and 2874NE, 3 bar for 2800BD, 2800XA & 2800XP 5 bar for 2800HP above the maximum seal chamber pressure, unless other values have been given. The maximum barrier pressure should be within the published seal operational limits. Consult the System Instruction Manual for pressure and alarm settings.
Under some circumstances very low ambient temperatures can result in the pressure in Plan 53A and 53B Barrier systems to reduce below the seal chamber pressure. With a Plan 53A ensure the pressurizing gas system isolation valve is never left closed. If a 53B system is operated with the ‘fill isolation valve’ closed (note, some auto-fill systems operate with this valve open) there is a risk of low ambient temperatures causing the barrier pressure to drop below the chamber pressure. An alternative gas charge pressure is then required; consult John Crane.
ATTENTION
Special gas pre-charge precautions are advisable when commissioning the accumulator in a Plan 53B. Consult the System
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Instruction Manual
Edition 7.6
Notes on decommissioning The seal chamber must be safely completely depressurized and emptied of process fluid before the seal is removed. If the process vapour is hazardous the machine casing must be purged with an inert gas before working on the seal. If the machine and any auxiliary equipment have been used on toxic or hazardous fluids, ensure all precautions are taken to avoid personnel hazards, such as correct decontamination. Note, fluid is often trapped during draining and may exist outside the seal. The relevant rotating machinery manual should be consulted to check for any special precautions.
seal leakage rate and any change from normal leakage rates. barrier gas flow for gas lubricated seals Condition of alarm signals Possible blockage of any strainers, magnetic filters, cyclones, coalescers or any other filters used. Vibration levels in the machine. Vibration levels are a good indicator of the condition of the machine and high levels can have a direct affect on seal and bearing life e.g. - Operation of the machine beyond its Allowable Operating Range (AOR) will increase vibration unacceptably. - Sleeve retention socket set screws can be loosened by high vibration. - Worn bearings can develop into catastrophic seal and machine failure. Monitoring vibration levels and
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Edition 7.6
check monthly buffer gas flow when applied, Wear parts for dry contacting containment seals require replacement after 24000 hrs dynamic operation. Check monthly, where appropriate, flow rates for Plans 32, 54, and 62 are at the required values.
Shaft temperature fluctuations, over a period of time, may reduce the original socket set screw friction. This is a risk on all pumps with a process temperature >150oC (300oF). Refer to Section 5.3.1 Vibration from unplanned or poor machine operation and high levels of start/stop can, over a period of time, loosen socket set screws and other fasteners.
Steadily increasing leakage rate normally indicates a seal failure condition and attention is required. If the fault cannot be remedied a repair will be required. If the buffer or barrier liquid systems need replenishment this should only be done with fill systems that exclude air ingress and/or prevent gas leakage to the atmosphere. If the barrier system pressure cannot be maintained at the correct value during topping up then the machine must be
Coalescing filters on gas barrier systems require either replacement or regular maintenance with the machine out of service. Consult the system Instruction Manual. Check and adjust torque on external drive collar socket set screws annually.
When repairing the rotating machine ensure all dimensions controlling the
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Instruction Manual
Edition 7.6
Rebuilding seals to as-new specifications must be carried out by qualified personnel.
Note:
7.3
It is recommended that a low pressure integrity test is carried out after repair and before installation on the machine.
8
Malfunction, Causes and Correction
John Crane must be consulted in the event of any malfunction of the sealing installation or sealing system. Excessive leakage rate, premature failure, high relative temperatures are all considered examples of abnormal malfunction.
Spare Parts
Only John Crane spare parts should be used to recondition seals. It is advised to stock on site a spare seal cartridge or the minimum replacement parts shown on the installation drawing (Section 9). The order codes for spare parts can be found in the parts list on the installation drawing. (Section 9 and the front page). In the case of gas lubricated seals only complete cartridges should be stored.
9
Accompanying Documents Seal Installation Drawing. See front sheet for specific drawing reference number. Seal Data Sheet (if applicable)
