Trip of tanker "Volgoneft 123" to repair base at the port of Astrakhan was successfully completed
On December, 5, 2007 trip of tanker "Volgoneft 123" to repair base at the port of Astrakhan was successfully completed. Tanker was damaged during Kerch storm on November, 11.
One-way trip project was carried out by the Marine Engineering Bureau (MEB) and was approved by Head Office of RRR.
The trip through Azov Sea (port of Caucasus - port of Azov) was carried out on November, 25 by tug-boat towing. The vessel continued her voyage through inland waterways by herself.
MEB carried out an analyze of damaged vessel strength. This analyze showed that vessel's hull in dangerous section satisfied requirements of O-PR class when hull girders with damages or crack were excluded from calculated model. For this situation special ballast loading condition was prepared for decreasing still water forces.
Ultimate strength calculations were based on the results of actual thickness measurement carried out be the specialists of CJSC "Nefteflot" (Samara) in September, 2007. Dangerous sections on fr. 97, 142 and 151 were tested in detail on the November, 20.
Measures due to decreasing loads onto damage sections (fr. 97 and 146-147) have been taken during designing of one way trip project. Big sagging which is usual for ballast condition of prj. 550А/1577 tankers could result in huge crack opening and evolution. The same time big hogging could result in increasing of longitudinal members buckling failure zone.
Water ballast was taken into all ballast tanks arranged in the cargo area (2710 tons). More over ballast water was taken into cargo tanks 5 & 6 (200 tons) and 7 & 8 (400 tons) so hull bending moments were decreased practically down to zero.
Voyage though sea was carried with the restrictions as follows:
- permissible 3% probability wave height of 1.5 m;
- permissible term of voyage is from November, 20 till December, 10 of 2007;
- towage by tugboat with capacity not less than 1000 kWt of RRR class M-SP 3.5 and higher, and with bollard pull not less than 110 kN at speed of 6 kn.
Cracks ends were drilled.
There was no cargo onboard because 4077 tons of masout were successfully reload into mv "Volgoneft 249" in the safe region of Caucasus port on the November 13. Stores of fuel oil and lub oil were minimal.
Tanker surveying for one time trip and Towage Certificate issuing was carried out by Don-Kuban branch of RRR.
Sea-going tug "Mercuiy" was used as a tug-boat for towage port of Caucuses - port of Azov. "Mercuiy" belongs to the Administration of the Tuanse port, her capacity is of 3650 kWt, RS class is KM I, registry No. is 731081, built in Yugoslavia.
Actual wave height didn't exceed permissible value during 12-hour trip through Azov Sea.
On arrival to the port of Azov Vessel was surveyed by specialists from RRR branh. Alternations in the damaged constructions and cracks growing were not found.
On the 28th of November vessel continued her voyage though inland waterways (Don River, Volgo-Don Canal, Volga River).
Tanker "Volgoneft 123" (prj. 550A, RRR register number is of 161651) was delivered on 01.07.75 in Bulgaria (building number is of 58). The vessel belongs to CJSC "Sudokhodnaya kompaniya "BashVolgotanker". Tanker was loaded by 4077 tons of masout about. RRR class is of M-PR 2.5.
3% probability wave height for sailing in permitted sea regions and M-PR region is not bigger than 2.5 m.
Signs of hull breakage at two sections (fr.97 and fr.147-148) have appeared while being on the anchorage at the situation of force 7 storm. Shell of the upper deck had got deformations in form of smooth dents and bulges. Deformations increased in transverse direction progressively. Height of deformations was of 30-100 mm. Cracks were found in the zone of deck buckling failure.
There was sagging of the vessel's hull so cracks openings were insignificant and was no cargo leakage, more over because crack didn't exceed sides.
At the zone of deformations on the fr.147-148 at the CL two cracks were found. First crack was of cross-form with dimensions of 300x300 mm and with opening up to 8 mm. Second crack was of 60 mm length with opening of 0.5 mm. Two more cracks of 300 mm and 60 mm length were found on the II belt of StB at fr. 148. Longitudinal corrugated bulkhead was deformed and there was buckling failure of underdeck girders with horizontal deflection up to 25 mm.
Transverse corrugation (fr.147-148) was stopped by two longitudinal laid on plates which were mounted during ship repair. This laid on plates were arranged onto deck stringer from aft superstructure till practically midship.
In the deformation zone two cracks of 150 mm (opening of 1 mm) and 60 mm length (opening 0.5 mm) were found on the III belt of StB at fr. 97.
Due to crew actions during heavy storm conditions on the November 11 vessel and her cargo were kept undamaged, people and environment didn't suffered.
"Volgoneft-123" voyage was finished in the port of Astrakhan on the 5th of December.