|PN||pipeline components material||allowable working pressure in the pipeline (bar) at a temperature (°C)|
|armatura z kołnierzami||screws acc. to |
DIN 2507 s. 23)
|Grey cast iron 4)||ductile iron4)||cast carbon steel||steel||201)|
2) resistance to 120 ° C: for liquid
3) the strength of the bolts is given to a temperature 15 ° C below the working temperature,
4) for valves of cast iron should be considered standard operating pressures (eg. to DIN 3201)
5) for soft gaskets or made of soft metal, screws C35 should be used,
*) allowable operating pressure for fittings with GG-20 and screws 5D take as up to 200 ° C.
|Pressure||Saturation temperature||Pressure||Saturation temperature|
Installation, Operating, and Maintenance Manual for Sight Glass Fittings Type 520, 530, 531
It is mandatory that you read this installation and maintenance manual ! It will be dangerous if you don’t read this !
This manual is also available as a PDF file available here.
1. Important Safety Information and Safety Instructions
1.1 Area of Application and Intended Use
The sight glasses may only be used as intended. Any applications beyond this will be considered to be usage not according to the intended purpose, and the manufacturer will not be liable for any resulting damage. Users will bear any risks in that case. Any unauthorized mechanical or structural modifications of the sight glasses will exclude any manufacturer liability for damage resulting from the modifications.
The intended use also includes compliance with manufacturer conditions for the intended installation, operation and maintenance (operating manual) as well as the consideration of foreseeable misconduct. The sight glasses have been supplied with information labels that must be observed.
1.2 Important Safety Information and Safety Instructions
1.2.1 Basic Safety Information
Statutory accident-prevention regulations as well as any other generally recognized safety-related, occupational health provisions must be observed. Any usage beyond this will be considered to be contrary to the intended use. The manufacturer shall not be liable for any damage resulting from this. The operating manual is part of the scope of delivery. If the sight glasses are resold, it must be handed over to the new owner.
To ensure safe operation, the sight glasses may only be used, maintained or repaired by specialized and trained staff members.
Qualified staff members include individuals who are aware of relevant standards, regulations, accident-prevention provisions through their training, experience and instruction, which entitles them to perform the necessary activities and enables them to recognize and avoid any potential hazards.
The operator must make sure that the individuals assigned to operate, service, and maintain the sight glasses have read and understood the operating manual and that they will observe it in every respect, so:
- they will avoid any hazards for health and lives of users and any third parties
- exclude any downtime and environmental impact by false handling.
Work responsibilities must be defined clearly and complied with, so there is no uncertainty where safety matters are concerned.
Any work on sight glasses may only be performed during a standstill of the system or when lines are free from any media. In places where lines can be opened or filled, signs must be set up which indicate clearly that work is being performed on the sight glasses.
After any maintenance work all disassembled protective devices must be properly reassembled. Protective devices and their protective effects must be checked by an expert before start-up of the machine.
Any warranty claims become void if:
- Damage occurs because of improper operation,
- Damage occurs because of improper storage,
- Repairs or interventions are performed by unauthorized individuals,
- Accessories and spare parts are used that are not compatible with the sight glasses,
- If no original spare parts are used.
Any failures must be reported immediately upon their detection. The sight glasses must be labelled appropriately. Any defects must be repaired immediately, so the damage is kept to a minimum and the safety of the machine is not impaired. In the event of non-compliance any warranty claims will become void.
The manufacturer reserves the right to any modifications in the sense of technical improvements.
1.2.2 General Safety Instructions
These safety instructions are by no means exhaustive. If any questions or problems occur, please contact the manufacturer.
The sight glasses have been built using state of the art technology. They are delivered in a reliable state.
The sight glasses may only be installed and operated according to the conditions laid down in the performance and supply contract.
Any retrofitting, modification or conversion of the sight glasses is prohibited as a matter of principle. You should consult the manufacturer in any case.
1.2.3. Special Safety Instructions
Any instructions affixed directly on the sight glasses, such as type plate, warning instructions, etc. must be observed. They must be free from paint and dirt. Missing signs must be replaced.
Sight glass plates/fittings must be handled with special care:
Relevant safety regulations – particularly for pipes under pressure and temperature and their elements – must be observed.
Observe item 4 before the first start-up !
Observe items 5 and 6 when cleaning and maintenance are performed !
Any assembly and maintenance work may only be performed when pipes are not under pressure and when they have cooled down. Supply lines must be closed reliable. This also applies to discharge lines in case of back pressure.
Only use original spare parts.
Under operation the sight glass fittings are under internal pressure. They are usually hot! If maintenance is performed during operation of the system, there is a risk of serious burns and acid burns from leaking medium.
Always wear protective clothing and goggles !
2. Product Description and Purpose
Sight glass fittings are built into pipes (flanged, screwed, or welded). Their purpose is to enable the operator of the plant to perform a visual inspection of the medium flowing through the piping - as far as quality and quantity are concerned. For that purpose the fittings have been provided with two opposite sight glass plates.
For information on the design, dimensions and materials please refer to the relevant data sheets.
Before leaving our company all fittings must have been examined in a "pressure test with sample pressure", acc. to the requirements of the DGRL (see appendix I, sections 3.2.2 and 7.4 of the DGR“ as presently valid) and the AD2000 flyer HP 30 for pressure vessels (section 4.17) with 1.43 times the highest permissible pressure.
For that purpose we apply the higher demands acc. to section 6 of the AD2000 flyer, but this “pressure test with sample pressure” for tightness is performed with water and 1.50 times the highest permissible pressure at 20°C (or appropriate special arrangements).
3. Storage and Transport
The fittings are to be packaged properly and transported and stored in a way to protect them against dirt and moisture. In particular, the glass plates must be protected against external impact and scratching.
Storage: Between 0° and +40°C in a clean and dry room.
Storage time: 2 years at the most. Then the seals must be checked and replaced as needed.
Varnish: Cast iron and cast steel fittings have been provided with a primer that is to protect them against corrosion through transport and storage only.
So, don’t damage the primer. Condensation of water must absolutely be avoided.
Don’t remove protective caps until just before the assembly, to avoid damaging the sealing surfaces. In case of improper storage any warranty claims become void.
4. Proper Use and Choice of Materials:
Operating area and choice of materials are subject to the operator’s or plant designer’s responsibility. Dimension regulations of the pressure equipment directive as presently valid must be observed !
4.1 Body Material and Seals
They must be selected carefully and the flow-through medium as well as the operating conditions (pressure and temperature) must be considered.
4.2 Glass Plates
4.2.1 Soda-lime glass acc. to DIN 8902: max. 150°C
4.2.2 Borosilicate glass acc. to DIN 7080: max. 280°C
In low temperature areas there are threshold values for the glass plates.
However, the AD2000 flyer W 10 for body and screw materials must be observed !
4.2.3[nbspThe additional protection of the sight glass place through mica discs is recommended, especially when a demineralised condensate/steam mixture and pH values higher than approx. 8 occur.
4.3 Pressure and Temperature Limits According to EN 1092
The lowest value in the combination “body – seals – glass plates” determines the maximum permissible threshold values as far as temperature and pressure are concerned. In case of doubt: Check with us !
5. Installation and First Start-up:
5.1 Installation Positions
The installation position is discretionary (except for designs with flap: Horizontal or vertical with upward flow-through).
5.2 Direction of Flow
Where an embossed or engraved directional arrow exists for the flow direction, this must be observed in any case.
5.3 Before the Installation
Before the installation of sight glass fittings you must make sure that pipes and fittings are free from any contaminations.
Any transfers of piping tensions to the sight glass fittings through the assembly procedure must be avoided.
5.5 Protection of Sealing Surfaces
Don’t remove protective caps until just before the assembly, to avoid damaging the sealing surfaces.
5.6.1 Flanged Connection
Piping flanges must be concentric and plane-parallel. The flange size and the shape of the sealing surface must match the sight glass fitting (refer to DIN 2526). Distance of piping flanges = overall length of the sight glass fittings + 2 x seal thickness. The connecting bolts must be tightened in a crosswise sequence, step by step and evenly (refer to the image in item 7). The torques mainly depend on the sealing material used.
5.6.2 Female thread connection
The female thread of the sight glass fitting must match the male thread of the piping, depending on the kind, size, and gradient. During the screwing in the sight glass fitting must be held with a suitable open-end wrench or pliers directly at the end to be screwed in. Never hold it on the sight glass lids, because the glass might break.
5.6.3 Welded fittings
Before welding the welding ends of the sight glass fittings and the pipes must be cleaned thoroughly and checked to see if they match (diameter, welding chamfer, etc.). Welding may only be performed by qualified staff members with appropriate welding procedures and welding materials according to welding regulations. Electric welding is to be preferred.
Attention: Sight glass plates and seals must be removed or covered on the inside and outside before welding, to protect them against welding gas and welding spatters. - Refer to item 7: Replacement of sight glass plates .
5.7 First Start-up
5.7.1 Before the first start-up the torques of the fastening screws of the two sight glass lids must be checked and corrected (especially after long storage times !). The procedures and torques listed in item 7 (replacement of sight glass plates) must be followed !
5.7.2 After the first load with pressure and temperature a certain “setting” of the seals is to be expected. Therefore the torques of the fastening screws of the sight glass lids, as described in item 7, must be checked and corrected again, as needed, in a cold and pressureless condition.
6 Maintenance and Servicing
6.1 Sight Glass Fittings don’t require any special maintenance.
6.2 Servicing of the Sight Glass Plates
If the sight glass plates are dirty on the outside they may be cleaned carefully. The glass surfaces must never be scratched (risk of breaking !). Conventional cleaning agents, especially glass cleaners, may be used. Use a clean and soft cloth !
6.3 Internal Contaminations
Internal contaminations of the sight glass plates may be removed as described under item 6.2. If the contaminations cannot be removed through cleaning the sight glass plates must be replaced.
The sight glass plates must also be replaced if they have been damaged by the flow or an aggressive medium and their surface has become rough (risk of breaking !).
For the new assembly of cleaned or new sight glass plates you must always use new seals in an appropriate quality. Refer to item 7 (replacement of sight glass plates) and item 1 (safety instructions)
6.4 General Instructions:
Even though sight glass plates are highly resistant acc. to DIN 8902 and DIN 7080 they are wear parts with a limited life. This depends in a high measure of the specific stress during operation.
6.5 Glass abrasion
7 Replacement of Sight Glass Plates
All work must be performed by qualified staff members, and the safety instructions in item 1 and below must be observed ! - Glass plates must be handled with special care !
7.2.1 Removal of Cover Flanges
Loosen the fastening screws of the cover flanges in several steps and crosswise. Remove cover flanges.
7.2.2 Removal of the Sight Glass Plate
Remove the sight glass plate as well as the internal seal and the intermediate layer on the side of the lid.
7.2.3 Preparation of the sealing surfaces
Carefully clean the sealing surface on the body as well as the supporting surface in the cover flange, removing sealing remainders. Check for damage (grooves, erosions, impact spots, etc.). Both surfaces must be absolutely clean, level and free from damage !
7.3.1 Insertion of the new sight glass plate
Insert the new internal seal (on the media side) and the new sight glass plate with proper dimensions and quality exactly in the centre. The marking on the seal and the glass plate must show outward. The seal may not project into the view diameter d1. - The glass plate must show a consistent gap with reference to the cylindrical sight glass cut out on the complete external diameter. It should be approx. 1 – 1.5 mm. The glass plate and the metal body may never touch each other !
Because of the different thermal expansion coefficients this would lead to damage and failure of the glass plates !
7.3.2 Insertion of the Glass Pad
Insert the external intermediate layer (cover side pad) and the sight glass lid exactly centred on the glass plate. The gap of approx. 1 – 1.5 mm mentioned above that must remain between the glass plate and the cover flange must always be observed.
7.3.3 Insertion of Cover Flanges
Screw in the fastening screws carefully and slightly tighten them manually. - The seal, the glass plate, the intermediate layer and the cover flange must not be moved ! The threads and the bearing surfaces of the fastening screws must have been lubricated with temperature-resistant thread paste (such as OKS ANTI-Seize paste), to avoid erosion and to guarantee defined friction values.
7.3.4 Tightening of the Screws
|Now all screws must be tightened in several small steps and crosswise (according to the image), using a torque wrench and the torques listed in the table below. All screws must show exactly the same tightening torque to avoid glass tensions !|
Torques in [Nm] – for the cover screws for lubricated screws and for standard graphite seals.
ø d2 [mm]
ø d1 [mm]
|4x M8||4x M10||4x M12||4x M14||4x M16||8x M16|
Correction factor for other seal materials:
|PTFE:||above values x 0.5|
|Aramid fibre:||above values x 0.7|
|Viton, silicone, EPDM etc.||above values x 0.6|
|Other:||available on request|
Note: When you use sight glasses with a PN > 40 or a special design, the torques must be obtained from the manufacturer.
7.3.5 Second, opposite side of sight glass
Disassemble and reassemble as described under 7.3.1 through 7.3.4.
7.3.6 Final Inspection
Finally you must check the tightness of the fitting ! The fitting must at least be examined in a "pressure test with sample pressure", acc. to the requirements of the DGRL (see appendix I, sections 3.2.2 and 7.4 of the DGR“ as presently valid) and the AD-2000 flyer HP 30 for pressure vessels (section 4.17) with 1,43 times the highest permissible pressure.
7.3.7 After Start-up
After the first re-start-up you must check the cover screws acc. to item 5.7 in a cold and pressureless condition and correct them as needed, because new sealings may "set".
|Material Number||DIN naming schema|
While every attempt has been made to verify the source of the information, no responsibility is accepted for accuracy of data.