Effectively Control The Remaining Length of The Fiber To Ensure The Safety of Submarine Cable

Submarine fiber optic cable is the throat of the global communication and information network, submarine fiber optic cable will be because of its own production process and quality reasons, man-made, and the impact of nature and injury break, resulting in communication information interruption. Civilian submarine cable interruption, will lead to the loss of contact between lovers and break up; military communications submarine cable interruption, will affect the fate of the country and even the survival of life and death. Industry insiders know that the delicate and fragile quartz glass filament, the reason why it can be used to make fiber optic cable without breaking, in addition to relying on the strengthening of material protection, more importantly, is to rely on a reasonable length of fiber optic residual. From the sea cable design, production, transportation, construction, operation, maintenance of the various stages of the sea cable in the fiber optic length will be a little bit of consumption. How to ensure the quality and safety of the sea cable through reasonable control of fiber length? 

This article from the sea cable design, production to the application of the process to explain:

1. Design stage

1.1 Remaining length of optical fiber in fiber optic casing and remaining length of optical fiber in the finished fiber optic cable

Because of the fiber optic residual length of the submarine cable once in the design stage is determined, and in the production of fiber optic loose casing in the process of curing, and thereafter the production, storage and transportation, construction, operation, maintenance phase, the fiber optic residual length will be a little eaten up, if the design of the residual length is unreasonable, then the submarine cable in the process of operation will be easily damaged because of the external forces. According to industry experience, the land cable will take into account the laying method (direct burial, overhead, pipeline), the use of the environment (special harsh environments such as high and low temperatures), geographic location (South, North) and other factors, generally the fiber optic cable in the fiber optic residual length control in the 2 ~ 5 ‰ between. However, the maximum of 5 ‰ of the sea cable after the length of some cases and can not meet the safety requirements. Fiber aftermath is divided into primary aftermath and secondary aftermath. The so-called primary residual length, refers to the production of fiber optic casing in the process of pulling the process of residual length, refers to the relative length between the optical fiber and the loose casing. In the process of producing loose casing, once the residual length is fixed, it can't be changed, and it will only decrease gradually. Secondary residual length, refers to the process of producing the core with a residual length of the loose casing stranded using the “SZ” form of winding around the center of the process of strengthening parts, is the relative length of the loose casing relative to the cable sheath. Center tube cable has no secondary length.

1.2 Reasonable design in the design process of the fiber optic length

1.2.1 For the southern sea area of the sea fiber optic cable, the fiber optic length should be appropriately increased; for the northern sea area, especially the winter ice sea fiber length should be appropriately reduced.1.2.2 Manufacturing submarine optoelectronic composite cables, the fiber optic length should be considered larger.

1.3 Reasonable design of fiber optic casing waterproofing process of submarine fiber optic cable in the external force, the outer layer of the cable armored steel wire will be extended, if the fiber is stressed, the two sides of the fiber will be migrated to the stress point. However, due to the existence of static friction between the thixotropic fiber paste and the optical fiber, preventing the optical fiber, especially for long distances, from moving; in addition, the waterproof pressure-resistant layer of the sea fiber optic cable will be stronger than the ordinary waterline cable. Therefore, the use of dry loose casing water blocking process will be conducive to the movement of optical fiber in the loose casing.

1.4 Reasonable design of the structure of the marine fiber optic cable core In view of the aforementioned loose-sleeved stranded fiber optic cable has a secondary residual length, in order to avoid the marine fiber optic cable in the receipt of more than the rated tension of the external force, the optical fiber residual length will not be quickly consumed and fiber breakage, so in the production of the marine fiber optic cable using loose-sleeved stranded fiber optic cable core structure, and reasonable control of the loose tube SZ winding pitch.

1.5 Reasonable design of submarine cable steel wire armor layer structure as a result of the submarine cable using multi-strand anticorrosive high-carbon steel wire winding outside the core to strengthen the protective effect, but once more than the rated tension, the steel wire from the helical distribution tends to be straight, the submarine cable will inevitably be elongated and broken fiber damage. Therefore, the design of sea cable steel wire armor layer, one is to try to choose high-strength steel wire, the second is to try to improve the pitch, the third is to try to use a double layer of steel wire using the “SZ strand” in the form of a single layer of steel wire structure in the force of the cable core is more likely to be elongated resulting in fiber interruption.

2. the production process

2.1 Strictly in accordance with the design requirements to control the length of the optical fiber

2.1.1 Accurately control the drawing precision of the loose casing to ensure that the remaining length of the optical fiber is produced according to the design;

2.1.2 Reasonable control of the cooling water temperature in the front and rear sections of the cooling water tank, to ensure the uniformity of the fiber before and after the remaining length;

2.1.3 accurately control the consistency of multiple optical fiber release tension, to ensure that the remaining length of the optical fiber in the same cable remains consistent, to avoid small remaining length of the optical fiber before the rated tension breaks.

2.2 Strengthen the test to ensure that the remaining length of the fiber to meet the design requirements In reality, the design and control of the remaining length of the fiber is one thing, and the actual production of fiber optic casing and cable is not to meet the design requirements of the remaining length of the cable is another matter. So in the ordinary cable production process, the fiber optic length is not within the scope of mandatory testing; and the sea cable fiber optic length, it is necessary to mandatory testing.

3. the storage and transportation process due to the high strength of the sea fiber optic cable, the diameter is much larger than ordinary fiber optic cable; and because the sea fiber optic cable according to the use of the length of customized, must be delivered to the continuous length of the sea fiber optic cable, so the length of the sea fiber optic cable can not be used for the transport of the cable tray packaging. Sea fiber optic cable in the production, dock delivery process, we must pay attention to the following links:

3.1 transfer sea fiber optic cable roller between the distance between the rollers can not be too large, to keep the roller smooth, bearing hold dead roller should be replaced in a timely manner to repair;

3.2 cable storage pool should be stocked with water, to avoid sea fiber optic cable stacked too many layers when the lower layer of sea fiber optic cables are squeezed and injured;

3.3 delivery of the sea fiber optic cable at the front end of the wheel diameter should be large enough to keep the roller group to guide the sea fiber optic cable The angle of the roller group to guide the sea cable should also be large, to avoid the sea cable loading and unloading storage and transportation process because the bending radius is too small and deformation of the force injured.

4. the construction of the laying process

4.1 cable laying route to the seabed geological stability, the seabed is relatively gentle no trench without shipwrecks;

4.2 cable depth to meet the design requirements, too shallow is easy to be anchored by the ship or aquaculture fishing tools hooked bad;

4.3 seabed rocky exposed areas, it is necessary to fill the concrete to prevent ocean currents and waves to promote the marine fiber optic cable has been damaged by friction on the rocks;

4.4 sea cable laying to be Into a large S-shaped deployment, local force when the sea cable itself free to adjust to ease the force;

4.5 sea cable landing on the shore to be pre-buried high-strength large-diameter cement piles, the sea cable wrapped around a few turns in the piles, to prevent the sea cable pull off the force of the land on the sea, land cable joints;

4.6 in the landing manhole, the sea cable to do enough to make a large enough reservation to ensure that access to the ODF frame of the fiber optic pigtails have a sufficiently long surplus.

5. the sea cable repair

5.1 sea cable repair process, towing the sea cable on the repair ship in the process, to set up a number of floats in the sea to withstand the tension caused by the weight of the sea cable, to prevent the repair process leads to the cable joints on both sides of the sea cable tension over the standard injuries;

5.2 sea cable repair in the sea cable repair, the length of the new sea cable should be much greater than the damage to the sea cable to be replaced by the length of the section, in order to ensure that the repair process and the repair is completed! Laying to the seabed after this section of the sea fiber optic cable is not stressed;

5.3  a section of the sea fiber optic cable is damaged, it means that the region of the sea fiber optic cable is easy to be damaged, so after the sea fiber optic cable repair, it should be properly rushed to deep trench burying or reinforcing the sea fiber optic cable, rather than directly thrown into the sea.