It is true that the situation you have mentioned above indicates that you are a very good and valuable employee for the company. However as you have indicated that you are not getting any promotions or appraisals, we need to look into the details you have mentioned to pin point the problem.
While all the attributes you have mentioned above are remarkable and appreciable, one needs to acknowledge the fact that sometime you need to be more open and communicative in order to make yourself visible to the employer. It is true that no one is comfortable blowing his own horn, but subtle reminders of how your performance has benefited the company can help you in getting that promotion. Staying out of office politics is a wise decision but you need to make sure that you do not completely avoid socializing with the colleagues while trying to keep clear of politics.
Taking initiatives is also an important part of professional success as the employers are looking for the person who is ready to take up additional work and enjoys a challenge. There are many people in the job market who are good at performing the tasks listed in the job requirements but they do not necessarily reach the highest point of professional success. So next time a big assignment comes up and the boss is looking for some additional help, make sure that you are the first one to volunteer.
Lastly, you can always ask the boss for a promotion and if he refuses, rather than getting angry or feeling disappointed, make sure that you ask your boss what changes he would like to see in your performance for a better future at the company and work on your waeknesses.
All the best,