In the world of the Feral Ork, the Pigdoks act as spiritual shamans and primitive Painboyz, but they also have a Mekboy equivelent. These are the Boiler Boyz and they handle the arts and crafts of building ramshackle medieval steam engines. They create awesome shit like the Steam Gargants and the like. Usually a Boiler Boy is accompanied by his servants/lesser underlings called Spanna Boyz who assist their boss in carrying his equipment around and acting as a secondary hand.
Like their more advance space faring cousins, the Mek Boy and the more Big Mek, the Boiler Boy has an affinity towards technology. Of course the Feral Orks' lower technological level means that the machines crafted by a Boiler Boy shows its simplicity in design.
Boiler Boyz are so named because the machines they work with runs off steam-power. As steam-power requires a ton of water and a mechanism to boil the liquid water into steam to generate energy, the Boyz who work in creating these engines earned their namesake. A lot of the crazy contraptions developed by the Boiler Boyz is all aimed towards siege warfare. This is unsurprising given the technological level of these Orks. Thus, siege engines such as catapults, trebuchets, ballistas, battering rams and siege towers are all weapons built by Feral Orks to wage large-scale warfare. However, a Boiler Boyz' greatest achievement is in the creation of the aforementioned Steam Gargant which is essentially a moving machine with every single siege weapon imaginable be fitted in the vehicle. It may require multiple Boiler Boyz from down to a few to several dozen along with hundreds of Spanna Boyz and Grot Styboyz to plan, construct and maintain these behemoths.
As such, Boiler Boyz provide an important structure in a Feral Ork tribe and without them, they would be stuck perpetually in the neolithic age. Due to their overall importance and affiliation, Boiler Boyz have a rivalry with the Pigdoks.