In the most rule requirements, the presence of the surveyor is required at times when materials or parts manufactured at places other than the shipyard are being installed aboard the ship concerned. The general conceptual flow of the acceptance inspection process is shown as below:
Presentation of list
Before the start of construction of the ship, a request should be made to the shipyard to submit a list of hull assembly units, equipment and materials which are brought-in or manufactured by a sub-contractor and intended to be used in the ship. These must be subjected to an acceptance inspection as mentioned above.
Omission of witness inspection
Depending on the items, if copies of stamp marks and labels can readily be correlated with the certificates, no witness inspection need be requested. Note, however, verification of the contents of the certificates should be made randomly or intently.
Note, however, that the proposed frequency of witness inspection has been determined on the assumption that the quality control level of the shipyard is generally acceptable. If any failure in such quality control activities is found, appropriate recommendations should be made for improving the situation, and witness inspections should be arranged on a continuous basis until the necessary improvement is realized in accordance with
the surveyor’s recommendation.
Example of an Acceptance Inspection
The aim of the acceptance inspection is to identify the brought-in materials or parts and their certificate (in case of rolled steel such as plates, sections, pipes, the certificates are called the “ Mill Sheets ” ), issued by the NK branch office where the materials were inspected.
a) Items to be inspected are steel plates, section bars and pipes used in hull construction. the steel products used for partition walls in living quarters, funnels etc. are normally not included in the acceptance inspection.
b) In principle, rolled steel materials to be used for a vessel should be inspected at least 3 times, per ship. In the inspection, a check should be made to verify if the rolled steel materials in question are the ones which passed the tests and inspection in the steel mills by the surveyor and which have a mill sheet issued by the Society.
Not only are there thickness differences but also many kinds of steel materials are used for one ship, such as mild steel of A, B, D and E grades, and high tensile steel of A, D and E grades, therefore, rolled steel must be strictly stored and controlled by the shipyard to avoid misuse. The surveyor should pay considerable attention to the control system applied for steel materials at the shipyard.
c) A request should be made to the yard to submit drawings containing data and information regarding the type and grade of steel, plate number and place of use, and checks should be made to ensure that the materials are being correctly used.
d) It may be acceptable to leave to the shipyard the responsibility of removing the mill sheet identification number (trace-ability) from the used steel materials and of reporting the correct compliance with the requirements for using the steel materials accordingly.
Cast steel and Forged steel
a) Items to be inspected are stems, stern frames, rudder stocks, coupling bolts of rudders, pintles, component parts of rudder horn, shaft brackets, valves, and cargo gear fittings required by the Rules.
b) At the time of the acceptance of those items mentioned above by the shipyard, a request should be made to the shipyard to submit the report on the results of the acceptance inspection, and copied stamp marks on material items specifically requested by the Rules.
c) No mark shifting, in principle, is necessary on each material item of which verification has been completed. Whenever the stern frame, rudder stock and other vital components are subjected to a rough machining and finishing process, a request should be made to the shipyard to submit the record of the results of the inspection by the shipyard, and a witness inspection should be made if it is found to be necessary.
Example of marking positions:
All welding materials used must be approved ones.
Generally, approval marks are printed on the box containing the electrodes, wire, flux etc. Before the start of construction of a ship, a request should be made to the shipyard to submit a list of the brands of welding rods, wires for semi-automatic welding, core wires and flux for automatic welding with supplementary information regarding the combination of these items and their classified use. Checks should be made to see if they are all in accordance with the requirements of the Society. Drying facilities and the quality control of welding materials are to be investigated at the early stage of construction.
Materials for fire protection
a) In general these materials are already accepted by the Society and their approval marks will be printed on the box, bag etc. The acceptance inspection is to confirm the approval marks.
b) Items to be inspected are as follows : Class A and B panels, deck coverings, paint (including lining materials), wooden sparrings, vapour barriers, fire resistant materials etc. A request should be made to the shipyard to submit a list of material brands for items to be used aboard the ship, together with reports on the results of inspection by the shipyard. Checks should then be made to verify that the approved materials have been purchased by the shipyard.
Anchors, anchor chain cables and mooring and towing ropes
The type and weight of anchors, the grade, diameter, and total length of chain cables, number, diameter, and length of ropes are shown in the approved Midship Section. The surveyor should confirm the acquisition of these items referring to the certificates, and examine any damage which may have occurred during transportation to the shipyard.
The following side scuttles are to be inspected according to the Rules. Other windows are outside the scope of the survey.
Overboard discharge valves should be made of approved materials, such as cast steel or copper alloy, and in principle they must meet the requirements of JIS (Japanese industrial Standards) or equivalent standards.
Those to be fitted below the load water line should be subjected to hydrostatic testing. General requirement : “ Valves and distance pieces fitted to the ship’s side below the load line are to be subjected to a hydrostatic test at a pressure of 1.5 times the designed pressure or 0.5 MPa, whichever is the greater. ”
Blocks (Hull assembly units)
A request should be made to the shipyard to submit a report on the hull assembly units which will be fabricated outside the shipyard. After delivery to the shipyard the surveyor has to examine their tested mark stamps, check the entries in the inspection records issued by the surveyor in charge and check for any damage caused during transportation.
In addition to the above, the following items may be manufactured in places other than the shipyard and approved by the Society with certificates. For these items, a request should be made to the shipyard to submit the report of the results of the acceptance inspection and the certificates to check their contents. On items subject to operation tests and water tightness tests after fitting aboard the ship, verification of the pass mark stamp should be made at an appropriate time.
(a) Deck cranes
(b) Steel hatch covers
(c) Watertight doors
(d) Steering gear
Additional knowledge with Propeller/Chain manufacturing & inspecting work flow:
Most of above is the general knowledge that a hull surveyor should be aware and noted, hope it’s easy to understand and to compile your knowledge.