Doc. No.
SOP/20
Standard Operating Procedure (SOP) Page 1 of 1
Rev. No. 0
Painting of FRP Membrane Housings st
21 April
Rev. Date 2025
1. Purpose
To establish a standardized method for the painting of FRP membrane housings using putty and
topcoat only, ensuring a consistent surface finish, protection, and visual appeal.
2. Scope
This SOP applies to all FRP membrane housings manufactured at UKL Instruments Pvt. Ltd. that
require surface finishing without the use of primer.
3. Responsibility
- Painter / Operator: Execute the painting process as per SOP
- Production Supervisor: Monitor adherence to process and verify setup
- Quality Inspector: Inspect finish quality and thickness
- Maintenance Technician: Maintain spray booth and equipment
4. Equipment and Materials
- Certified Spray Paint Booth (Clean & Ventilated)
- Approved Putty for FRP Surface
- Paint
- Paint Spray Gun
- Mixing Station
- PPE (Mask, Goggles, Gloves, Coveralls)
- Sandpaper 120 Grit
- NC Thinner, Cloth, Tape for Masking
- Paint Thickness Gauge (Calibrated)
5. Safety Precautions
- Use full PPE at all times.
- Ensure the booth exhaust and filters are working.
- Keep fire extinguishers nearby.
- No open flames or smoking.
- Follow MSDS guidelines for chemicals used.
6. Procedure
6.1 Pre-Inspection
- Verify Batch number product tag, paint code, and job traveler.
- Check Substrate surface for cracks, dust, or contaminants.
- Ensure booth and equipment are functional and clean.
6.2 Surface Preparation
- Record Environment temperature, Dew point and humidity.
- The ambient temperature is less than 4°C.
- The relative humidity is more than 85 percent.
- The surface temperature is less than 3°C above the dew point.
- Clean housing surface with NC Thinner (degreaser) and cloth SSPC SP1 solvent
cleaning.
- Mechanical power cleaning may be used for ST3 and ST2.
- Sand the surface using 120 grit paper for leveling to achieve ST 2 / ST3 cleanliness.
- Wipe dust with dry cloth.
Prepared By Approved By
(QA Manager) (MD)
Signature:
Date: Date:
Doc. No. SOP/20
Standard Operating Procedure (SOP) Page 2 of 1
Rev. No. 0
Painting of FRP Membrane Housings st
21 April
Rev. Date 2025
- Mask non-paintable areas.
6.3 Putty Application
Mix putty thoroughly as per TDS.
Apply evenly using a putty knife or spatula.
Allow to dry completely minimum 30 min.
Sand again with fine grit 120 grit for smoothness.
Clean housing surface with water.
Ensure a clean, even surface before painting.
6.4 Painting (Topcoat Application)
- Mix topcoat paint and hardener in specified ratio as per TDS.
- Strain and load paint into spray gun.
- Apply 2–3 uniform coats, allowing flash-off between each.
- Maintain spray distance: 15–20 cm.
- Record booth Environment temperature and humidity.
6.5 Curing
- Allow painted part to hard dry for 8 Hrs.
- Do not handle until Hard dry.
- Move to drying/curing rack.
7. Inspection & Quality Checks
Checkpoint Criteria
Visual Finish No sagging, runs, or orange peel
Paint Thickness 80–120 µm
Color/Gloss White/Glossy
Record all results in the Paint Inspection Log.
8. Documentation
- Production & Inspection Report
Paint, Thinner & Hardener Batch Record
Painter Details
Inspection details of QA
- Non-Conformance Report (if applicable)
9. References
- Specification
- Paint & Putty TDS/MSDS
Prepared By Approved By
(QA Manager) (MD)
Signature:
Date: Date:
