How to restrict BOM explosion in Quotation and Sales Order

Dear all,

How can we restrict BOM main item explosion in Sales Order.

this BOM main item is having special order items which have to generate purchase requisition (item category - BANC),

with out exploding bom main item, can we generate a purchase requisition for BOM subitems, can any body explain me that how can we do that.

your suggestions will be highly appreciated.

thank you

Raghu Ram