Diesel Hammers: Pileco

Above: Pileco D-8 diesel hammer on Vulcan Foundation Equipment’s excavator mast, ready to drive below grade. Photo courtesy of Vulcan Foundation Equipment.

Since we dealt with older European diesel hammers in the post Diesel Hammers: Delmag, Nilens and the Method of Analysis, let’s turn to something more contemporary: Pileco diesel hammers, one of several organisations which market the Delmag-derived diesel hammers from China. Conroe-based Pileco has a long history with diesel hammers, having been a Delmag distributor since those hammers were first introduced into the United States. They also led in introducing diesel hammers to the offshore oil industry, where they became a standard for driving oil drilling casing.

We can start by presenting the same analysis for hammers ranging from the D-12 to the D-80 as we had in Diesel Hammers: Delmag, Nilens and the Method of Analysis:

Model	Pileco D-12-42	Pileco D19-42	Pileco D25-22	Pileco D36-32	Pileco D-46-32	Pileco D-62-22	Pileco D-80-23
Ram mass, kg	1250	1900	2500	3600	4600	6200	8000
Compression volume, mm3	1776360	2584240	4218030	5830520	7520020	11094000	14155100
Ratio of compression volume to ram mass, mm3/kg	1421.1	1360.1	1687.2	1619.6	1634.8	1789.4	1769.4
Cylinder diameter, mm	300	320	419	500	500	550	630
Cylinder cross-sectional area, mm2	70686	80425	137885	196350	196350	237583	311725
Probable working stroke from GRLWEAP data, mm	356	422.91	373.888	375.92	481.076	578.866	581.914
Actual expansion volume, mm3	26912243	36596680	55771684	79642239	101979072	148622689	195551969
Ratio of Free Air Volume to ram mass, mm3/kg	21530	19261	22309	22123	22169	23971	24444
Actual compression ratio	15.2	14.2	13.2	13.7	13.6	13.4	13.8
Maximum Physical Stroke, m	3.597	3.840	4.176	3.993	3.810	3.810	3.932
Maximum Energy from Maximum Physical Stroke, kJ	44.1	71.6	102.4	141.0	171.9	231.7	308.6
Actual Working Volume, m3	0.0251	0.0340	0.0516	0.0738	0.0945	0.1375	0.1814
Ratio of actual working stroke to cylinder diameter)	1.19	1.32	0.89	0.75	0.96	1.05	0.92
Initial Pressure (p1), MPa	0.101	0.101	0.101	0.101	0.101	0.101	0.101
Gas Constant k	1.25	1.25	1.25	1.25	1.25	1.25	1.25
Compression Pressure (p2), MPa	3.030	2.784	2.556	2.662	2.638	2.598	2.700
Maximum Combustion Pressure (p3), MPa	10.86	10.86	9.31	9.83	9.83	10.00	9.72
Ratio of Combustion Pressure to Compression Pressure	3.58	3.90	3.64	3.69	3.73	3.85	3.60
Total Thermodynamic Energy, kJ	27.437	40.443	54.185	80.168	103.540	156.738	191.373
Ratio of Thermodynamic Energy to Maximum Stroke Energy	62.21%	56.50%	52.91%	56.85%	60.22%	67.64%	62.02%
Mean Effective Pressure from Energy and Actual Working Volume, kPa	1091.562	1189.069	1051.039	1086.114	1096.141	1139.674	1054.995

Some notes and comments about this result are as follows:

• The data from which this is derived is from the GRLWEAP database. That includes the maximum combustion pressure.
• From higher compression ratios in the smaller hammers, the compression ratio in the larger ones settle down to vary between 13 and 14.
• The gas constant drops from 1.35 (as assumed from WEAP87) to 1.25. This is in line with the Russians‘ assumption all along.
• The initial pressure is assumed to be atmospheric, in accordance with GRLWEAP’s assumption. I think there is merit in the Russians‘ assumption that this will be elevated a little with backpressure during downstroke and blowdown, but I’ve stuck with GRLWEAP’s assumption here. It’s worth noting that, at higher elevations, this will in reality drop.
• The maximum pressures are larger than they were in Diesel Hammers: Delmag, Nilens and the Method of Analysis. There are many possibilities for this, including better measurement techniques, but one factor is that it is possible today to more precisely machine and hone large bores than it was forty years ago, which reduces break-in times and improves the sealing possibilities of the piston rings.
• The mean effective pressures are consistently above 1000 kPa/1 MPa.
• The ratio of thermodynamic energy to maximum stroke (“catch ring”) energy varies between 50% and 70%, which is overall higher than we have seen with any of the hammers we have analysed.

The impression for this data shows a technology that has improved over time.