No header, but the framing still needs to be strong enough to hold the weight of the materials above it.
A typical load bearing header will be 2 2x12s with a 7/16 plywood spacer between them.
I would install studs, or struts, on each side of the pipe in question.
No.
header
Outside wall, inside partition wall, usually down the center of the house, header over a door or window, top and bottom plate in the wall, the floor the wall sits on, the rim joist the wall sits on, the floor joists, these are all horizontal load bearing features.
A wall bearing no load.
You must temporarily support the framing above on each side of the wall, then emplace an adequately sized header to support the load, and transfer that load appropriately. Contact a qualified carpenter or seek the advice of a structural engineer.
Load Bearing - something that bears a load. Like a load bearing wall in a house. The wall is holding something up like the roof, another floor, etc.
The part of the framing above a window opening is known as the lintel. It is a horizontal structural element that supports the load from above, helping distribute the weight of the structure evenly.
The load bearing center wall could be opened up by installing properly spaced support posts that rest on sufficiently sized concrete footings with appropriately sized header beams.. A quick visit by a structural engineer will help you determine how and if this is possible in your situation.
Usually, a load bearing wall will be perpendicular to the roof ridge.