The name Bertha, after Seattle's first female mayor, , was chosen by a panel (that included the Governor and Transportation Secretary) from 150 submissions from kindergarten through 12th graders, who were asked to submit female names with Washington state heritage. The winning entry, which was submitted by two elementary schools in and , was selected in December 2012.
[pdf] Compared with the drill and blast method, TBM tunnelling has significant advantages with high construction efficiency, low project cost, conducive to environmental protection, favorable stability contr.
[pdf] This article lists the main components of a petroleum onshore drilling rig. Offshore drilling rigs have similar elements, but are configured with a number of different drilling systems to suit drilling in the marine environment. The equipment associated with a rig is to some extent dependent on the type of rig but. .
1. 2. 3. (mud pump)4. 5. .
• (#22) is a section of large diameter pipe fitted to the top of the that the attaches to via a side outlet, to allow the to flow back to the .• (BOPs) (#23 and #24) are devices.
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