Security?

This blog is actually about a work project on the site to repair the main entrance gates but I don't feel I can adequately cover the topic without discussing the concept of security here in Tanzania to a Tanzanian.  The concept of keeping what is mine is strongly ingrained into most of Africa.  Yes in most of the world people take common sense measures to protect things they own like lock their doors when they leave or lock up their cars. So what I have been struggling with as I worked on rebuilding the gate is the misconception of security here by creating items of show instead of items of real physical security.  

The rebuilt gate after being primed and 1st coat of paint

Let me start by telling you what was asked for in our gate and then describing to you the reality of the situation.  While determining the project and how to best utilize our resources those from the Tanzanian side of the discussion talked about a strong, secure gate that would prevent bullets from hitting someone behind the gate, stopping a vehicle trying to ram the gate,  secure locking mechanism that are boxed so no one can access the locks easily making it harder to cut them off, that it have sharp points along the top to prevent people from climbing over it were the general direction of comments I got.  I talked about an attractive gate that utilized the majority of items I could salvage from the original gate that fell apart including the square tubing posts with gaps between them.  I wanted to make structural changes to the frame of the gate which would be the part we would be building new so the thin metal components would not break under the overall weight of the gate as it did before. I also felt it would be good to put the flat panel higher up so that it could be our site signage and put the square tube posts below and above.  This was fought hard as the night guard was worried that someone might shoot him in the foot or knee through the gaps in the tubes (originally the flat  panel was the lowest part and about chest level it started with the posts and gaps meaning if someone shot you through the gaps they would do so in the chest or head).  Of course I have not seen anyone in the valley who owns a gun to begin with.  Most violent crime in rural areas involve a hoe, shovel, machete, or large stick.

The original gate-the main body broke from the unit attached to the hinges because the weight of the gate put too much stress on the thin metal and welding of the thin metals.

A weld break

broken metal and welds from the weight

Now for the reality of the situation that I have use many times to try and explain why the gate does not need to be strong enough to defend against an M1 Abrams tank attack is that three feet past the gate we go to barbed wire fencing that is spaced at about 14 inches apart and is very easy for goats and calves to get through and therefore easy for a man to get through.

the barbed wire fence  next to the security gate

Ok enough of the commentary, now on to the rebuild of the gate.  As I said I wanted to reuse as much of the non-structural or filler material as possible to save money and cut down on the metal waste as well because their is not a Jim in the Mauldin United Methodist Men's Fellowship to haul it off to a recycling center because there is no recycling center.

The original unit was made of a 1" square tubing all the way through with a 2 mm wall thickness, the same as the flat plate steel. There are two gates swinging on hinges that are 7 feet high and 6 feet wide.  One gate had a personnel walk through door which was made of the same materials and standard hinges.  This walk through door was end the furthest away from the main gate hinges.  Because of this, the moment force on the hinges and the bar attached to the hinges was much higher than if the door was closer to the hinges.  When figuring a structural item that is attached on end like a cantilever the force at the unattached or unsupported end is the weight or force down TIMES the distance from the support and that is the moment force which is represented as being circular in nature not straight down.  Basically the gates were heavy enough they created a significant enough moment force that the steel used to make them could not support that force.

In the rebuild I used 1 1/2" square tubing with a wall thickness of 3mm.  This unfortunately is the thickest wall tubing I can obtain.  The only thing I can get with a thicker wall is black pipe in 2" diameters but that would not work well for our gate.  Because of this I decided to reinforce the connection using 1 1/2 flat bar with a 4 mm thickness and allowing me to create longer welds around the connections.  In addition I used 2" flat bar to create corner supports in a triangle form.

reinforcing the connection with a flat bar that is thicker

reinforcing the corner using flat bar

I reused the walk through door as already built and used the 1 1/2 square tubing with flat bar reinforcement as the frame for the door.  We then cut off all the 1" square tubing filler and flat plate so we could reuse them on the new unit.  The difficult part of this was that they were so thin our welder at its lowest setting would often burn through them leaving holes.  Fortunately none of this is structural but fills the large open spaces and can be the part most people will see.  I did use some bolts to attach the plate because I did not have a rivet tool but I did find one in Arusha this weekend and purchased it to touch up the plate some.

cutting out the filler from the old gates

using bolts to help in areas where the welding was burning holes in the plate

The left frame with walk through door frame installed on hinges

right frame installed on hinges

The left frame and the right frame were build slightly different.  The left frame the hinges were such that we could build the frame and then attach the frame part of the hinges and slide them over the concrete structure hinges.  The right frame the hinges  both faced in forcing us to weld the hinges on while holding the part of the frame they attached to up.  So I built the left frame on the ground and then installed.  the right frame had to be built while from the hinge bar out while hanging on the hinges.  That was a much tougher build.

We also touched up the concrete and brick structures by applying a concrete plaster to the surface that will be painted after it has properly cured (at least 7 days but prefer 14).

After the gates were installed we added slide bolts to secure them and then I placed a bolt with a nut that was welded to the frame then built concrete bases where the gates will stop both closed and open.  The purpose was that the bolt will be screwed down on these stops or more specifically the piece of metal I set in the concrete relieving the moment force stress off the hinges.

bolt with welded nut

concrete base with metal plate inset for the resting part of the gate function

The gate closed with the bolts on the concrete base

had to make a temporary tool for the night guard to turn the bolts until I can find a wrench that size in town.

In addition to the work on the main gate we had a personnel gate in another location with the slide bolt to secure it on the side facing out instead of inside the perimeter where we needed it so I installed one on the correct side and started painting that gate as well.

This week also built some clothes lines for the staff to dry their clothes/sheets on.