6 Bulkhead Connection to Lower and Upper Stool

6.1 Design standard J, K and L

6.1.1

The welded connection of bulkhead to lower stool of bulk carriers and oil tankers are to be designed according to the design standard J and K respectively, as shown in Table 10 and Table 11.

6.1.2

The welded connection of bulkhead to upper stool of bulk carriers are to be designed according to the design standard L, as shown in Table 12.

Table 10 : Design standard J – transverse bulkhead connection detail, bulk carrier (Ballast hold)

Connections of transverse bulkhead with lower stool
Critical areas	Design standard J

Critical locations

Critical location	Connections of lower stool shelf plate to lower stool and corrugated transverse bulkheads. C Connections of shedder plates to corrugated transverse bulkhead.
Detail design standard	The use of scallops is to be avoided on diaphragms/web at lower stool top plates. Gusset plates are to be fitted to corrugated bulkheads. Gusset plates are to be made out of the same material and have the same asbuilt thickness as corrugated bulkheads; and, the height of gusset plates is to be greater than half of breadth of the corrugation. To reduce stress concentrations at the crossing of the shedder plates one plate is to be moved higher than the other (as shown in Figure). Alternatively, bracketed stiffener can be fitted at the crossing points underneath the shedder plating facing the ballast hold.
Building tolerances	Ensure alignment between lower stool sloping plates and corrugation faces according to IACS Recommendation No. 47.
Welding requirements	Full penetration welding is to be applied between lower stool top plates and the side plating of lower stools and corrugated bulkheads. Partial or full penetration welding is to be applied around gusset plates. However, full penetration welding is to be applied between lower stool top plates and gusset plates. Ensure start and stop of welding is as far away as practicable from the critical corners.

Table 11 : Design standard K – transverse or longitudinal corrugated bulkhead connection detail, oil tanker

Connections of transverse or longitudinal bulkhead with lower stool
Critical areas	Design standard K

Critical locations

Critical location	Connections of lower stool top plate to corrugated transverse or longitudinal bulkheads.
Detail design standard	The use of scallops is to be avoided on diaphragms/web at lower stool top plates. Supporting brackets are to be fitted in line with corrugation web as required in Ch 6, Sec 4, [2.6.2]. Scallop is not permitted in the supporting bracket.
Building tolerances	Ensure alignment between lower stool side plates and corrugation faces according to IACS Recommendation No. 47.
Welding requirements	Full or partial penetration welding is to be applied between lower stool top plates and the side plating of lower stools. Full penetration welding is to be applied between lower stool top plates and vertical corrugated bulkheads. Full or partial penetration welding is to be applied between lower stool top plates and supporting brackets. Ensure start and stop of welding is as far away as practicable from the critical corners. Connection ‘J’, as shown in the figure, of in line supporting bracket to stool top plate and side plate of lower stool is to be full or partial penetration welding, on minimum 300 mm from the corner.

Table 12 : Design standard L – transverse bulkhead connection detail, bulk carrier (Ballast hold)

Connections of transverse bulkhead with sloped plate of upper stool
Critical areas	Design standard L

Critical locations

Critical location	Connections of corrugated transverse bulkhead to the topside tank sloping plating and upper stool.
Detail design standard	The use of scallops is to be avoided on diaphragms/web at upper stool bottom plates. Gusset plates are to be fitted between the face plates of corrugated bulkheads in way of heavy ballast hold. In way of heavy ballast hold, a deep transverse web or well-stiffened backing stiffener is to be provided in the topside tank in line with the face plate of the bulkhead corrugations to ensure that the loads are effectively dissipated. Gusset plates are to have a thickness and material properties not less than those required for corrugation flanges.
Building tolerances	Ensure alignment between the face plates of corrugated bulkheads with the stool side plates as well as the watertight bulkheads and deep transverse web (or wellstiffened backing stiffener) in the topside tanks according to IACS Recommendation No. 47.
Welding requirements	Partial or full penetration welding is to be applied between upper stool bottom plates and corrugation. Fillet welding having minimum weld factor of 0.44 is to be applied between upper stool bottom plates and upper stool side plating. Fillet welding having minimum weld factor of 0.44 is to be applied between upper stool bottom plates and diaphragms/web rings. Ensure start and stop of welding is as far away as practicable from the critical corners in all holds.

Table 13 : Design standard M – connection details for vertically corrugated bulkheads in cargo tanks and heavy ballast hold

Connections of vertically corrugated bulkhead to inner bottom/hopper plating without stool
Critical areas	Design standard M
	Detail of in line bracket:
Critical locations	Detail of in line bracket:
	Note 1: Brackets are to be arranged below inner bottom and hopper tank plating in line with corrugation webs. Note 2: Where gusset plate with shedder plate according to Ch 6, Sec 4, [2.6.4] item b, is provided, in line bracket may be omitted on the side of gusset plate.
Critical location	Connections of corrugated transverse bulkhead to the topside tank sloping plating and upper stool.
Material and scantling requirement	Inner bottom and hopper tank plating in way of corrugations is to be in accordance to Ch 6, Sec 4, [2.6.4]. Floors/girders and hopper web that support corrugation flange is to be in accordance to Ch 6, Sec 4, [2.6.4]. Supporting bracket aligned with corrugation web is to be in accordance with Ch 8, Sec 2, [5.2] and Ch 6, Sec 4, [2.6.4].
Detail design standard	Supporting brackets are to be fitted in line with corrugation web as required in Ch 6, Sec 4, [2.6.2]. Scallop is not permitted in the supporting bracket.
Building tolerances	Median line of corrugation is to be in line with the median line of the supporting members with an allowable tolerance of t_as-built /3 or 5 mm, whichever is less, where t_as-built is the inner bottom thickness.
Welding requirements	For the connection of vertically corrugated bulkheads to the inner bottom/hopper plating, full penetration welding is to be provided in according to Ch 12, Sec 3, [2.4] For the connection of supporting structures to inner bottom/hopper plating, partial or full penetration welding is to be provided in accordance with Ch 12, Sec 3, [2.4]. Partial or full penetration welding is also to be applied for the connection of in line brackets below corrugation web in accordance with Ch 12, Sec 3, [2.4] on minimum 300 mm from the corner.