BACKEND PIPE SYSTEM

KEEP EYES ON YOUR BACKEND

The backend pipe system is a critical part of your boom system. This swing elbow, closest to the pump, experiences the highest pressures and pulsations — pressure spikes — during cylinder switchover. Each time the flow direction changes — particularly at 90-degree elbows and reducers — it creates a high-wear zone where the aggregate in the slurry causes impact wear and sliding abrasion against the inner wall of the component. The backend is also a location where many workers (drivers, inspectors and pump operators) are near these components under high pressure. Fortunately, it is also easily accessible and can be inspected regularly.

Since the end-of-job cleanout involves opening this elbow, daily visual inspections should be routine. After cleaning and prior to closing the backend, it should be visually checked for dents, cracks, wear craters or holes on the interior and exterior. Perform a closer inspection if any damage is found.

Coupling alignment is also important; make sure your gaskets and O-rings are not leaking. While the backend elbows are quite thick, they should still be routinely inspected. If the expected wear of the backend Concrete boom pump backend elbow is not known, inspections at least every 500 pumping hours is the recommended starting point.

HOW TO GET THE MOST LIFE FROM YOUR SYSTEM

Many variables account for the life of your pumping system’s hoses, pipes and elbows: yardage and mix design, to name a couple. One cause of wear often overlooked is pumping speed. Many operators look for a crew to pump as much concrete as quickly as possible, at times even outpacing the placement team and the job site’s concrete delivery. The faster the concrete flows, the higher the pressure and the more abrasion your delivery system will endure. This is not a one-to-one relationship; double the pumping speed equates to exponential wear on components. It only takes small adjustments to make a significant difference in the longevity of your components. Keep this in mind when you are scheduling jobs and planning a pour. By slowing down the pumping speed and pressures when practical, you can realize significant improvement in your boom system’s life. 

BACKEND INSPECTIONS

While there are some differences in what you should look for based on the elbow’s construction, many things are universal.  On the exterior, visually check for cracks and signs of damage. Specifically look for hammer marks; lines in the paint or concrete leaking from the welded joints that may indicate underlying cracks; and dents or gouges at the inlet and outlet connection end. If you notice seepage on the exterior of your backend elbow, this could also be a sign of porosity in the bend, and this area should be inspected more closely.

A steel access port is often welded onto the top of the elbow for use in pipeline priming and cleanout procedures. Due to the directional change and nearness to the pump, this location is one of high turbulence and pressure. While very useful in the functionality of the equipment, this option could be a location for early failure of the backend elbow. This accelerated wear is more pronounced in designs that are used with a shorter radius to the access port, which is common on some pumps. If you choose to include this port, you should be aware that it is a weak point and will require more careful inspection during cleanout.

Another component that demands careful and frequent inspection is the six-inch to five-inch reducer leading to the deck pipe. The pipe diameter reduction creates higher sliding velocity and mix turbulence that also increases wear. You should check the smaller end of this pipe frequently when the coupling is disengaged.

A note on CCI-lined backend elbows: In CCI-lined backend elbows, the outer shell has limited abrasion resistance. There is a grey epoxy material between the shell and liner in some manufacturers’ designs. When exposed, it will appear as a grey spot surrounded by the outline of the inner liner damage that has exposed it. Once the liner is worn and the filler epoxy is visible, the backend elbow must be replaced.

LINE PUMPING FROM BOOM PUMPS

Occasionally, some applications need to pump off the back of the boom pump using an adapter. The adapter must be secure in the mounting (sometimes tucked behind the swing elbow hinge) to withstand pumping pulsation. Make sure the adapter is secure before pumping with proper seals to prevent caustic concrete splashing. It is also important to make sure any connections made at the back of the pump are secured and supported to minimize movement while pumping. Movement in these components can accelerate wear on the raised ends where the clamps engage. This wear can round the edges on the raised end, making accidental clamp disengagement more likely in the event of a plug.

MAXIMIZING SAFETY AND EQUIPMENT

Safety glasses, gloves and a vest are key equipment to wear around the pump.  Hazardous conditions can occur quickly due to a leaking seal or when a backend component fails — work smart.  Long pants and correct footwear can reduce the risk of injury. It is also important to maximize the lifetime of your boom components; they are costly and critical to your operation. For those same reasons, proper inspections, operation and maintenance of your components are vital to keep your pumping crew safe and to avoid potential back charges from the concrete contractor. The cost of a single component failure can escalate significantly when factoring in lost productivity and worker safety. Ballistic covers can be applied to increase safety for everyone at the back of the pump in case of a failure. 

The ballistic cover also helps to identify leaks and may indicate that a closer inspection of the backend components is necessary. All backend components on the rear end of the truck should always be inspected for damage, due to contact with other vehicles or property in transit.

By prioritizing regular inspections, mindful operation and the right component choices, you not only extend the life of your boom system — but also protect your crew, your equipment and your bottom line.