Hull Structure, Class Surveys & RightShip · ESP Code & PSPC
ESP Code Hull Survey, Ballast Tank Coating (PSPC) & Thickness Measurement Guide (A.1049(27), MSC.461(101) & MSC.215(82))
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1. 2011 / 2019 ESP Code Corrosion Limits & Two-Surveyor Rule (SOLAS XI-1/2)
Under SOLAS Regulation XI-1/2, all single-side and double-side skin bulk carriers ≥ 500 GT and all double-hull and non-double-hull oil tankers ≥ 500 GT must be surveyed in accordance with the 2011 ESP Code (IMO Resolution A.1049(27)) as amended by the 2019 ESP Code (IMO Resolution MSC.461(101)). Understanding how class surveyors and PSC officers evaluate hull diminution prevents unexpected steel repairs and detentions:
| Corrosion Category & ESP Reference | Quantitative Threshold / CSR Limit | Survey & Maintenance Impact |
|---|---|---|
| Substantial Corrosion (2011/2019 ESP Code § 1.2.9 — IMO Res. A.1049(27) & Res. MSC.461(101)) | Corrosion wastage > 75% of allowable diminution margin (or between t_ren + 0.5 mm and t_ren on IACS CSR vessels) | Extent of corrosion such that assessment of the corrosion pattern indicates wastage in excess of 75% of allowable margins, but within acceptable limits. Any structural area identified with Substantial Corrosion becomes a "Suspect Area" requiring additional ultrasonic thickness measurements (UTM) and annual close-up examination at every subsequent Annual Survey until recoated or renewed. |
| Pitting Corrosion (2019 ESP Code § 1.2.18 & § 8.2 — IMO Res. MSC.461(101)) | Local material reduction ≥ 18% of as-built thickness; unacceptable if pitting intensity ≥ 15% over a 300 mm × 300 mm frame or pit residual thickness < 0.7 × (t_as-built - t_vol_add) or < 6 mm | Scattered corrosion spots/areas with local material reductions ≥ 18% of as-built thickness. For IACS CSR bulk carriers and oil tankers, steel renewal or welded repair is required if pitting intensity reaches or exceeds 15% on the standard 300 mm checker-board diagram or if individual pit thickness falls below minimum residual thickness. |
| Edge Corrosion (2019 ESP Code § 1.2.19 & § 8.3 — IMO Res. MSC.461(101)) | Residual free-edge thickness ≥ 0.7 × (t_as-built - t_vol_add); affected height ≤ 25% of web height (≤ 100 mm at openings); length ≤ 1/3 of stiffener span | Local corrosion at the free edges of plates, stiffeners, primary support members, and around lightening holes or manholes. Frequently affects cold-formed bulk carrier hold frames and ballast tank web cutouts. |
| Grooving Corrosion (2019 ESP Code § 1.2.20 & § 8.4 — IMO Res. MSC.461(101)) | Groove breadth ≤ 15% of web height or ≤ 100 mm; residual thickness ≥ 0.75 × (t_as-built - t_vol_add) and ≥ t_ren - 0.5 mm (min 6 mm); length ≤ 1/2 of member span | Localized linear corrosion occurring at structural intersections along weld toes due to weld heat-affected zone (HAZ) galvanic effects and stress concentration, particularly at bulk carrier lower hopper/stool knuckles and longitudinal bulkhead attachments. |
- Mandatory Two-Surveyor Rule (ESP Code § 1.4): At least two surveyors must attend on board simultaneously at every Renewal Survey and Intermediate Survey on bulk carriers and oil tankers
≥ 20,000 DWTstarting from Renewal Survey No. 3 (age> 10 years), and on single-side skin bulk carriers≥ 100,000 DWTat the Intermediate Survey between10 and 15 yearsof age, co-signing the survey report (§ 6.1.3). - Bottom Inspection in Dry-Dock (ESP Code § 2.2): There must be a minimum of two inspections of the outside of the ship's bottom during the 5-year renewal period at intervals not exceeding 36 months, and for ships of 15 years of age and over, inspection of the outside of the ship's bottom must be carried out with the ship in a dry-dock.
- Forward 25% Annual Hatch Cover Full-Travel Testing (ESP Code Annex A § 3.3.2): At every Annual Survey on bulk carriers, all mechanised hatch cover sets in the forward 0.25L (forward 25% of ship length) plus at least one rotating cargo-area set aft of
0.25Lmust be operationally tested from the stowed position to fully closed and weathertight secured.
2. PSPC Ballast Tank Coatings & Coating Technical File (MSC.215(82) / SOLAS II-1/3-2)
Under SOLAS Regulation II-1/3-2 (as amended by IMO Resolution MSC.216(82)) and the Performance Standard for Protective Coatings (PSPC, IMO Resolution MSC.215(82)), all dedicated seawater ballast tanks in ships ≥ 500 GT and double-side skin spaces in bulk carriers ≥ 150 m must be coated to a 15-year target useful life and documented in a permanent onboard Coating Technical File (CTF):
| Coating Rating / PSPC Standard | Quantitative Criteria | Survey Consequence & CTF Verification |
|---|---|---|
| GOOD Coating Condition (ESP Code § 1.2.10 & PSPC Res. MSC.215(82) § 4.1) | Spot rusting < 3% of area under consideration without visible failure of the coating; rusting at edges or welds < 20% of edges/weld lines | Target useful life under SOLAS Reg. II-1/3-2 (PSPC) is 15 years in GOOD condition. Ballast tanks maintained in GOOD condition remain on the standard 5-year renewal / intermediate survey examination schedule. |
| FAIR Coating Condition (ESP Code § 1.2.11) | Local breakdown of coating at edges/weld lines ≥ 20% and/or light rusting ≥ 3% but < 20% of the area under consideration; hard rust scale < 10% | Requires monitoring and touch-up maintenance under the ship's Planned Maintenance System (SOLAS II-1/3-2.4) to prevent deterioration to POOR condition. |
| POOR Coating Condition (ESP Code § 1.2.12 & § 2.3.1) | General breakdown of coating over ≥ 20% of areas or hard scale ≥ 10% of areas under consideration (or unpainted ballast tank) | Triggers mandatory annual internal examination of the seawater ballast tank at every Annual Survey (ESP Code § 2.3.1) on both bulk carriers and oil tankers, unless recoated and upgraded by the attending class surveyor. |
| PSPC Newbuilding & Repair Spec (IMO Res. MSC.215(82) § 2.8 & Table 1 / SOLAS II-1/3-2) | 320 µm epoxy NDFT (90/10 rule: ≥ 90% of readings ≥ 320 µm, none < 288 µm); Sa 2½ blast (30–75 µm profile); ≤ 50 mg/m² NaCl; ≤ 85% RH & ≥ 3°C above dew point | Must be documented in the permanent onboard Coating Technical File (CTF, MSC.215(82) §§ 3.4.1 & 3.4.5) verified by a certified NACE Coating Inspector Level 2 or FROSIO Inspector Level III (§ 6.1.1). |
3. Onboard ESP Survey Report File & Supporting Documents (§§ 6.2 & 6.3)
Port State Control officers and RightShip/SIRE inspectors verify that the Chief Officer and Master maintain the complete ESP Survey Report File ready for inspection on board:
- Core ESP Survey Report File (§ 6.2): Must contain (1) Reports of structural surveys, (2) the Condition Evaluation Report (Executive Hull Summary) issued upon completion of each Renewal Survey, and (3) Thickness Measurement Reports certified by an approved UTM firm and countersigned by the attending surveyor.
- Supporting Documents (§ 6.3): Must include the approved Survey Programme (submitted in advance of Renewal/Intermediate surveys), main structural plans of cargo holds/tanks and ballast tanks, previous repair history, cargo and ballast history, and the ship's log of crew structural inspections (leakage, structural deformation, coating breakdown, and inert gas plant operation).
- Ship Structure Access Manual (SSAM, SOLAS II-1/3-6 & MSC.1/Circ.1572/Rev.2): Verify that the approved 8-part SSAM is on board, that all horizontal access hatches (
≥ 600 mm × 600 mm) and vertical girder/floor openings (≥ 600 mm × 800 mm) and permanent ladders/walkways are free of wasted rungs or loose bolts, and that annual and pre-entry crew PMA inspections are signed in SSAM Part 2.
Questions seafarers ask
What documents must be kept in the onboard ESP Survey Report File under SOLAS XI-1/2?
Under the 2011/2019 ESP Code Sections 6.2 and 6.3 (IMO Resolution A.1049(27) as amended by Resolution MSC.461(101), mandatory under SOLAS Regulation XI-1/2 for bulk carriers and oil tankers ≥ 500 GT), the ship must keep on board an updated ESP Survey Report File containing: (1) Reports of structural surveys, (2) the Condition Evaluation Report (Executive Hull Summary) issued at completion of every renewal survey, and (3) Ultrasonic Thickness Measurement (UTM) reports. It must be accompanied by supporting documents: the Survey Programme, main structural plans of cargo holds/tanks and ballast tanks, previous repair history, cargo and ballast history, and inspector records of inert gas,涂层/coating condition, and structural defects.
When does the mandatory Two-Surveyor Rule apply during ESP hull surveys?
Under 2019 ESP Code Section 1.4 (IMO Resolution MSC.461(101)), at least two exclusive surveyors from the Administration or recognized classification society must attend on board simultaneously at every Renewal Survey and Intermediate Survey on all bulk carriers and oil tankers of 20,000 DWT and above starting from Renewal Survey No. 3 (ships over 10 years of age), and additionally on single-side skin bulk carriers of 100,000 DWT and above at the Intermediate Survey between 10 and 15 years of age. All attending surveyors must jointly sign the survey report (§ 6.1.3).
What happens if a seawater ballast tank coating is downgraded to POOR during a class survey?
Under ESP Code Section 2.3.1, if a dedicated seawater ballast tank on a bulk carrier or oil tanker is found with no protective coating, a soft/semi-hard coating, or a hard protective coating rated in POOR condition (general breakdown ≥ 20% of area or hard rust scale ≥ 10% of area) and is not restored, the ballast tank must be placed on Annual Examination and internally inspected by a class surveyor at every Annual Survey.
What are the SOLAS II-1/3-6 Ship Structure Access Manual (SSAM) opening dimensions and crew inspection rules?
Under SOLAS Regulation II-1/3-6 and the Technical Provisions (IMO Resolution MSC.158(78), introduced by Resolution MSC.194(80) for oil tankers ≥ 500 GT and bulk carriers ≥ 20,000 GT), ships must carry an approved 8-part Ship Structure Access Manual (SSAM). Horizontal access hatches and manholes must have a minimum clear opening of 600 mm × 600 mm, and vertical openings through web frames, floors, and girders must have a minimum clear opening of 600 mm × 800 mm at a height ≤ 600 mm from the bottom shell plating. Under MSC.1/Circ.1572/Rev.2, crew must log annual and pre-entry inspections of Permanent Means of Access (PMA) in Part 2 of the SSAM.
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