Prepare CSP 3–4. Choose coating by chemistry exposure: Polyurea for fast heavy‑duty, Coal Tar Epoxy for external chemical zones, 2K cementitious for internal lining. Arrest leaks by PU/VA injection first. Band joints and penetrations. Record DFT and adhesion.
LQ-STP-ETP
Summary
STP/ETP leakages combine continuous immersion, chemical attack, and negative pressure during outages. Systems must resist sewage/effluents and maintain bond under hydrostatic head.
Symptoms
- Dampness around tank walls and base slab
- Leaks at pipe inlets/outlets and construction joints
- Coating blistering or softening in contact zones
Probable causes
- Incompatible/under‑spec coatings for chemical exposure
- Insufficient surface prep; osmotic blistering
- Joint treatment missing or failed; cracks under load
Solution paths
- Positive‑side heavy‑duty membrane or coating
- Injection grouting for active leaks at joints
- Internal negative‑side cementitious/crystalline only as supplementary where positive side cannot be reworked
Recommended technologies
- Polyurea (2–3 mm) fast‑cure, abrasion and chemical resistant
- Coal Tar Epoxy high‑solids for external/chemical zones
- 2K cementitious (potable/non‑potable grades) for internal lining where compatible
- PU/Vinyl acrylate injection grouts for running leaks
Quick SOP
1) Stop inflow; clean/degrease; shotblast/abrade to CSP 3–4; repair defects.
2) Prime per manufacturer; spray polyurea or apply coal tar epoxy to specified DFT; stripe coat corners.
3) Band/bridge construction joints and penetrations with compatible system; inject where active leaks persist.
4) Cure; re‑commission with staged fill test.
QA / acceptance
- DFT logs; adhesion ≥1.5 MPa; chemical spot tests; 24–72 hr fill test
Video Masterclass
SpecX Masterclass: STP / ETP Leakages Solutions — Coming Soon
Disclaimer
SpecX is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.