## 2 Fire-Resistance Performance of A60 BPP  
### Fire-Resistance Design and Regulation  
The A60 BPP, which is installed on ships and offshore plants, is a fire-resistance apparatus used for the safe operation of control and communication cables and connected through the vertical bulkhead structure while maintaining airtightness in case of fire accident in the bulkhead compartment. Figure 1 shows the design specifications for bulkhead penetration pieces specified in the international ship classification regulations [15], according to the fire-resistance ratings.  
As shown in Figure 1, the steel body of A60 BPP should be designed with both lengths of 900 mm and a thickness of 3 mm, including insulation. In case that the length or the thickness does not meet the requirements specified in Figure 1, the modified A60 BPP design should be verified by fire test according to the FTP code [1; 2; 15]. However, as the length of A60 BPP increases, production and quality problems such as A60 BPP deformation, productivity decrement, and cable damage occur. Therefore, shipyards are actually having many difficulties in complying with the design regulations specified by the international ship classifications. In order to improve the productivity and quality of  
Figure 1: The fire-resistance rating of A-class bulkhead penetration piece.  
A60 BPP, the authors of this study devised a new design by means of reducing the body length of A60 BPP and applying the stepped sectional configuration of insulation. In this section, the fire-resistance performance of the newly devised A60 BPP was evaluated via the transient heat transfer analysis and the fire test verification. The enhanced design configuration of A60 BPP is shown in Figure 2.  
As shown in Figure 2, the body of the A60 BPP was reduced to 200 mm in length, and the diameter was designed to be \(\phi\)8 and \(\phi\)12 for the tube, and \(\phi\)20 and \(\phi\)25 for the body, respectively. The cross section of the insulation was designed to be the height of 90 mm for the width of 120 mm from the center of the A60 BPP, and the height of 30 mm in the other parts. Mechanical structural carbon steel (S45C) and austenitic stainless steel (SUS316L) were considered as materials for the A60 BPP, respectively.  
A60 BPP should be designed so that the temperature measured on the opposite side of the furnace inside is 180 \({}^{\circ}\)C or less for 60 min under the furnace heating condition regulated by the FTP. Figure 3 shows the configuration of the fire test specimen specified in the FTP code [2].  
As shown in Figure 3, the fire test specimen of A60 BPP should be made of a general steel structure material (SS400). For the rectangular plates with the width of 2440 mm, the length of 2500 mm and the thickness of 4.5 mm, L-shaped stiffeners with dimensions of 65 \(\times\) 65 \(\times\) 6 mm should be placed at 600 mm intervals. The A60 BPP was mounted with the insulation between the L-shaped stiffeners of the specimen, as shown in Figure 3, and the fire-resistance performance was verified through the fire test. For the fire test specimen equipped with both A60 BPP and the insulation, the side of the insulation should be placed on the opposite side of the furnace inside in order that the specimen can be evaluated in the same manner as operation condition in the actual ship. In addition, the specimen was mounted vertically in the furnace and heated gradually to the temperature of 940 \({}^{\circ}\)C for 60 min.  
Figure 2: Enhanced design configuration of A60 BPP.